Health Topics

Immune system

Immune System and Disorders
National Library of Medicine
Chronic Granulomatous Disease
SCID
Severe Combined Immunodeficiency
What is the immune system?

Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.

When germs such as bacteria or viruses invade your body, they attack and multiply. This is called an infection. The infection causes the disease that makes you sick. Your immune system protects you from the disease by fighting off the germs.

What are the parts of the immune system?

The immune system has many different parts, including:

  • Your skin, which can help prevent germs from getting into the body
  • Mucous membranes, which are the moist, inner linings of some organs and body cavities. They make mucus and other substances which can trap and fight germs.
  • White blood cells, which fight germs
  • Organs and tissues of the lymph system, such as the thymus, spleen, tonsils, lymph nodes, lymph vessels, and bone marrow. They produce, store, and carry white blood cells.
How does the immune system work?

Your immune system defends your body against substances it sees as harmful or foreign. These substances are called antigens. They may be germs such as bacteria and viruses. They might be chemicals or toxins. They could also be cells that are damaged from things like cancer or sunburn.

When your immune system recognizes an antigen, it attacks it. This is called an immune response. Part of this response is to make antibodies. Antibodies are proteins that work to attack, weaken, and destroy antigens. Your body also makes other cells to fight the antigen.

Afterwards, your immune system remembers the antigen. If it sees the antigen again, it can recognize it. It will quickly send out the right antibodies, so in most cases, you don't get sick. This protection against a certain disease is called immunity.

What are the types of immunity?

There are three different types of immunity:

  • Innate immunity is the protection that you are born with. It is your body's first line of defense. It includes barriers such as the skin and mucous membranes. They keep harmful substances from entering the body. It also includes some cells and chemicals which can attack foreign substances.
  • Active immunity, also called adaptive immunity, develops when you are infected with or vaccinated against a foreign substance. Active immunity is usually long-lasting. For many diseases, it can last your entire life.
  • Passive immunity happens when you receive antibodies to a disease instead of making them through your own immune system. For example, newborn babies have antibodies from their mothers. People can also get passive immunity through blood products that contain antibodies. This kind of immunity gives you protection right away. But it only lasts a few weeks or months.
What can go wrong with the immune system?

Sometimes a person may have an immune response even though there is no real threat. This can lead to problems such as allergies, asthma, and autoimmune diseases. If you have an autoimmune disease, your immune system attacks healthy cells in your body by mistake.

Other immune system problems happen when your immune system does not work correctly. These problems include immunodeficiency diseases. If you have an immunodeficiency disease, you get sick more often. Your infections may last longer and can be more serious and harder to treat. They are often genetic disorders.

There are other diseases that can affect your immune system. For example, HIV is a virus that harms your immune system by destroying your white blood cells. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). People with AIDS have badly damaged immune systems. They get an increasing number of severe illnesses.


Immune System Diseases
Immune System
Immune System
What is the immune system? Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other ...
Childhood Vaccines
National Library of Medicine
Immunization, Childhood
Vaccination
Shots
What are vaccines?

Vaccines are injections (shots), liquids, pills, or nasal sprays that you take to teach the immune system to recognize and defend against harmful germs. The germs could be viruses or bacteria.

Some types of vaccines contain germs that cause disease. But the germs have been killed or weakened enough that they won't make your child sick. Some vaccines only contain a part of a germ. Other types of vaccines include instructions for your cells to make a protein of the germ.

These different vaccine types all spark an immune response, which helps the body fight off the germs. Your child's immune system will also remember the germ and attack it if that germ ever invades again. This protection against a certain disease is called immunity.

Why do I need to vaccinate my child?

Babies are born with immune systems that can fight most germs, but there are some serious diseases they can't handle. That's why they need vaccines to strengthen their immune system.

These diseases once killed or harmed many infants, children, and adults. But now with vaccines, your child can get immunity from these diseases without having to get sick. And for a few vaccines, getting vaccinated can actually give you a better immune response than getting the disease would.

Vaccinating your child also protects others. Normally, germs can travel quickly through a community and make a lot of people sick. If enough people get sick, it can lead to an outbreak. But when enough people are vaccinated against a certain disease, it's harder for that disease to spread to others. This means that the entire community is less likely to get the disease.

Community immunity is especially important for the people who can't get certain vaccines. For example, they may not be able to get a vaccine because they have weakened immune systems. Others may be allergic to certain vaccine ingredients. And newborn babies are too young to get some vaccines. Community immunity can help to protect them all.

Are vaccines safe for children?

Vaccines are safe. They must go through extensive safety testing and evaluation before they are approved in the United States.

Some people worry that childhood vaccines could cause autism spectrum disorder (ASD). But many scientific studies have looked at this and have found no link between vaccines and autism.

Can vaccines overload my child's immune system?

No, vaccines do not overload the immune system. Every day, a healthy child's immune system successfully fights off thousands of germs. When your child gets vaccines, they are getting weakened or dead germs. So even if they get several vaccines in one day, they are being exposed to a tiny amount of germs compared to what they encounter every day in their environment.

When do I need to vaccinate my child?

Your child will get vaccines during well-child visits. They will be given according to the vaccine schedule. This schedule lists which vaccines are recommended for children. It includes who should get the vaccines, how many doses they need, and at what age they should get them. In the United States, the Centers for Disease Control and Prevention (CDC) publishes the vaccine schedule.

Following the vaccine schedule allows your child to get protection from the diseases at exactly the right time. It gives his or her body the chance to build up immunity before being exposed to these very serious diseases.


Immunization
Children and Teenagers
Infections
Immune System
What are vaccines? Vaccines are injections (shots), liquids, pills, or nasal sprays that you take to teach the immune system to recognize and defend against ...
Autoimmune Diseases
National Library of Medicine
Autoinflammatory Disorders
What are autoimmune diseases?

Your immune system protects you from disease and infection by attacking germs that get into your body, such as viruses and bacteria. Your immune system can tell that the germs aren't part of you, so it destroys them. If you have an autoimmune disease, your immune system attacks the healthy cells of your organs and tissues by mistake.

There are more than 80 types of autoimmune diseases. They can affect almost any part of your body. For example, alopecia areata is an autoimmune disease of the skin that causes hair loss. Autoimmune hepatitis affects the liver. In type 1 diabetes, the immune system attacks the pancreas. And in rheumatoid arthritis, the immune system can attack many parts of the body, including the joints, lungs, and eyes.

What causes autoimmune diseases?

No one is sure why autoimmune diseases happen. But you can't catch them from other people.

Autoimmune diseases do tend to run in families, which means that certain genes may make some people more likely to develop a problem. Viruses, certain chemicals, and other things in the environment may trigger an autoimmune disease if you already have the genes for it.

Who is at risk for autoimmune diseases?

Millions of Americans of all ages have autoimmune diseases. Women develop many types of autoimmune diseases much more often than men. And if you have one autoimmune disease, you are more likely to get another.

What are the symptoms of autoimmune diseases?

The symptoms of an autoimmune disease depend on the part of your body that's affected. Many types of autoimmune diseases cause redness, swelling, heat, and pain, which are the signs and symptoms of inflammation. But other illnesses can cause the same symptoms.

The symptoms of autoimmune diseases can come and go. During a flare-up, your symptoms may get severe for a while. Later on, you may have a remission, which means that your symptoms get better or disappear for a period of time.

How are autoimmune diseases diagnosed?

Doctors often have a hard time diagnosing autoimmune diseases. There's usually not a specific test to show whether you have a certain autoimmune disease. And the symptoms can be confusing. That's because many autoimmune diseases have similar symptoms. And some symptoms, such as muscle aches, are common in many other illnesses. So it can take a long time and some visits to different types of doctors to get a diagnosis.

To help your doctor find out if an autoimmune disease is causing your symptoms,:

  • Learn about the health conditions in your family history. What health problems did your grandparents, aunts, uncles, and cousins have? Write down what you learn and share it with your doctor.
  • Keep track of your symptoms, including how long they last and what makes them better or worse. Share your notes with your doctor.
  • See a specialist who deals with the symptoms that bother you most. For example, if you have rash, see a dermatologist (skin doctor).
What are the treatments for autoimmune diseases?

The treatment depends on the disease. In most cases, the goal of treatment is to suppress (slow down) your immune system, and ease swelling, redness, and pain from inflammation. Your doctor may give you corticosteroids or other medicines to help you feel better. For some diseases, you may need treatment for the rest of your life.


Autoimmune Diseases
Immune System
What are autoimmune diseases? Your immune system protects you from disease and infection by attacking germs that get into your body, such as viruses and ...
Vaccines
National Library of Medicine
Adult Immunization
Immunization
Vaccination
What are vaccines?

Vaccines are injections (shots), liquids, pills, or nasal sprays that you take to teach your body's immune system to recognize and defend against harmful germs. For example, there are vaccines to protect against:

  • Viruses, like the ones that cause the flu and COVID-19
  • Bacteria, including tetanus, diphtheria, and pertussis
What are the types of vaccines?

There are several types of vaccines:

  • Live-attenuated vaccines use a weakened form of the germ
  • Inactivated vaccines use a killed version of the germ
  • Subunit, recombinant, polysaccharide, and conjugate vaccines use only specific pieces of the germ, such as its protein, sugar, or casing
  • Toxoid vaccines that use a toxin (harmful product) made by the germ
  • mRNA vaccines use messenger RNA, which gives your cells instructions for how to make a protein (or piece of a protein) of the germ
  • Viral vector vaccines use genetic material, which gives your cells instructions for making a protein of the germ. These vaccines also contain a different, harmless virus that helps get the genetic material into your cells.

Vaccines work in different ways, but they all spark an immune response. The immune response is the way your body defends itself against substances it sees as foreign or harmful. These substances include germs that can cause disease.

What happens in an immune response?

There are different steps in the immune response:

  • When a germ invades, your body sees it as foreign
  • Your immune system helps your body fight off the germ
  • Your immune system also remembers the germ. It will attack the germ if it ever invades again. This "memory" protects you against the disease that the germ causes. This type of protection is called immunity.
What are immunization and vaccination?

Immunization is the process of becoming protected against a disease. But it can also mean the same thing as vaccination, which is getting a vaccine to become protected against a disease.

Why are vaccines important?

Vaccines are important because they protect you against many diseases. These diseases can be very serious. So getting immunity from a vaccine is safer than getting immunity by being sick with the disease. And for a few vaccines, getting vaccinated can actually give you a better immune response than getting the disease would.

But vaccines don't just protect you. They also protect the people around you through community immunity.

What is community immunity?

Community immunity, or herd immunity, is the idea that vaccines can help keep communities healthy.

Normally, germs can travel quickly through a community and make a lot of people sick. If enough people get sick, it can lead to an outbreak. But when enough people are vaccinated against a certain disease, it's harder for that disease to spread to others. This type of protection means that the entire community is less likely to get the disease.

Community immunity is especially important for people who can't get certain vaccines. For example, they may not be able to get a vaccine because they have weakened immune systems. Others may be allergic to certain vaccine ingredients. And newborn babies are too young to get some vaccines. Community immunity can help to protect them all.

Are vaccines safe?

Vaccines are safe. They must go through extensive safety testing and evaluation before they are approved in the United States.

What is a vaccine schedule?

A vaccine, or immunization, schedule lists which vaccines are recommended for different groups of people. It includes who should get the vaccines, how many doses they need, and when they should get them. In the United States, the Centers for Disease Control and Prevention (CDC) publishes the vaccine schedule.

It's important for both children and adults to get their vaccines according to the schedule. Following the schedule allows them to get protection from the diseases at exactly the right time.


Vaccination
Vaccines
Immunization
Infections
Immune System
... sprays that you take to teach your body's immune system to recognize and defend against harmful germs. For ...
HIV/AIDS Medicines
National Library of Medicine
AIDS Medicines
Antiretroviral therapy
What is HIV/AIDS?

HIV stands for human immunodeficiency virus. It harms your immune system by destroying CD4 cells. These are a type of white blood cells that fight infection. The loss of these cells makes it hard for your body to fight off infections and certain HIV-related cancers.

Without treatment, HIV can gradually destroy the immune system and advance to AIDS. AIDS stands for acquired immunodeficiency syndrome. It is the final stage of infection with HIV. Not everyone with HIV develops AIDS.

What is antiretroviral therapy (ART)?

The treatment of HIV/AIDS with medicines is called antiretroviral therapy (ART). It is recommended for everyone who has HIV. The medicines do not cure HIV infection, but they do make it a manageable chronic condition. They also reduce the risk of spreading the virus to others.

How do HIV/AIDS medicines work?

HIV/AIDS medicines reduce the amount of HIV (viral load) in your body, which helps by:

  • Giving your immune system a chance to recover. Even though there is still some HIV in your body, your immune system should be strong enough to fight off infections and certain HIV-related cancers.
  • Reducing the risk that you will spread HIV to others
What are the types of HIV/AIDS medicines?

There are several different types of HIV/AIDS medicines. Some work by blocking or changing enzymes that HIV needs to make copies of itself. This prevents HIV from copying itself, which reduces the amount of HIV in the body. Several medicines do this:

  • Nucleoside reverse transcriptase inhibitors (NRTIs) block an enzyme called reverse transcriptase
  • Non-nucleoside reverse transcriptase inhibitors (NNRTIs) bind to and later change reverse transcriptase
  • Integrase inhibitors block an enzyme called integrase
  • Protease inhibitors (PIs) block an enzyme called protease

Some HIV/AIDS medicines interfere with HIV's ability to infect CD4 immune system cells:

  • Fusion inhibitors block HIV from entering the cells
  • CCR5 antagonists and post-attachment inhibitors block different molecules on the CD4 cells. To infect a cell, HIV has to bind to two types of molecules on the cell's surface. Blocking either of these molecules prevents HIV from entering the cells.
  • Attachment inhibitors bind to a specific protein on the outer surface of HIV. This prevents HIV from entering the cell.

In some cases, people take more than one medicine:

  • Pharmacokinetic enhancers boost the effectiveness of certain HIV/AIDS medicines. A pharmacokinetic enhancer slows the breakdown of the other medicine. This allows that medicine to stay in the body longer at a higher concentration.
  • Multidrug combinations include a combination of two or more different HIV/AIDS medicines
When do I need to start taking HIV/AIDS medicines?

It's important to start taking HIV/AIDS medicines as soon as possible after your diagnosis, especially if you:

  • Are pregnant
  • Have AIDS
  • Have certain HIV-related illnesses and infections
  • Have an early HIV infection (the first 6 months after infection with HIV)
What else do I need to know about taking HIV/AIDS medicines?

It's important to take your medicines every day, according to the instructions from your health care provider. If you miss doses or don't follow a regular schedule, your treatment may not work, and the HIV virus may become resistant to the medicines.

HIV medicines can cause side effects. Most of these side effects are manageable, but a few can be serious. Tell your health care provider about any side effects that you are having. Don't stop taking your medicine without first talking to your provider. He or she may give you tips on how to deal with the side effects. In some cases, your provider may decide to change your medicines.

What are HIV PrEP and PEP medicines?

HIV medicines are not just used for treatment. Some people take them to prevent HIV. PrEP (pre-exposure prophylaxis) is for people who don't already have HIV but are at very high risk of getting it. PEP (post-exposure prophylaxis) is for people who have possibly been exposed to HIV.

NIH: Office of AIDS Research


HIV Infections
Antiretroviral Therapy, Highly Active
Anti-HIV Agents
Immune System
Drug Therapy
... stands for human immunodeficiency virus. It harms your immune system by destroying CD4 cells. These are a type of white blood cells that fight infection. The loss of these cells makes it ... gradually destroy the immune system and advance to AIDS. AIDS stands for ...
Shingles
National Library of Medicine
Herpes Zoster
Post-herpetic Neuralgia
Postherpetic neuralgia
What is shingles?

Shingles is an outbreak of rash or blisters on the skin. It is caused by the varicella-zoster virus - the same virus that causes chickenpox. After you have chickenpox, the virus stays in your body. It may not cause problems for many years. But as you get older, the virus may reappear as shingles.

Is shingles contagious?

Shingles is not contagious. But you can catch chickenpox from someone with shingles. If you've never had chickenpox or the chickenpox vaccine, try to stay away from anyone who has shingles.

If you have shingles, try to stay away from anyone who has not had chickenpox or the chickenpox vaccine, or anyone who might have a weak immune system.

Who is at risk for shingles?

Anyone who has had chickenpox is at risk for getting shingles. But this risk goes up as you get older; shingles is most common in people over age 50.

People with weakened immune systems are at higher risk of getting shingles. This includes those who:

  • Have immune system diseases such as HIV/AIDS
  • Have certain cancers
  • Take immunosuppressive drugs after an organ transplant

Your immune system may be weaker when you have an infection or are stressed. This can raise your risk of shingles.

It is rare, but possible, to get shingles more than once.

What are the symptoms of shingles?

Early signs of shingles include burning or shooting pain and tingling or itching. It is usually on one side of the body or face. The pain can be mild to severe.

One to 14 days later, you will get a rash. It consists of blisters that typically scab over in 7 to 10 days. The rash is usually a single stripe around either the left or the right side of the body. In other cases, the rash occurs on one side of the face. In rare cases (usually among people with weakened immune systems), the rash may be more widespread and look similar to a chickenpox rash.

Some people may also have other symptoms:

  • Fever
  • Headache
  • Chills
  • Upset stomach
What other problems can shingles cause?

Shingles can cause complications:

  • Postherpetic neuralgia (PHN) is most common complication of shingles. It causes severe pain in the areas where you had the shingles rash. It usually gets better in a few weeks or months. But some people can have pain from PHN for many years, and it can interfere with daily life.
  • Vision loss can happen if shingles affects your eye. It may be temporary or permanent.
  • Hearing or balance problems are possible if you have shingles within or near your ear. You may also have weakness of the muscles on that side of your face. These problems can be temporary or permanent.

Very rarely, shingles can also lead to pneumonia, brain inflammation (encephalitis), or death.

How is shingles diagnosed?

Usually your health care provider can diagnose shingles by taking your medical history and looking at your rash. In some cases, your provider may scrap off tissue from the rash or swab some fluid from the blisters and send the sample to a lab for testing.

What are the treatments for shingles?

There is no cure for shingles. Antiviral medicines may help to make the attack shorter and less severe. They may also help prevent PHN. The medicines are most effective if you can take them within 3 days after the rash appears. So if you think you might have shingles, contact your health care provider as soon as possible.

Pain relievers may also help with the pain. A cool washcloth, calamine lotion, and oatmeal baths may help relieve some of the itching.

Can shingles be prevented?

There are vaccines to prevent shingles or lessen its effects. The Centers for Disease Control and Prevention recommends that healthy adults 50 years and older get the Shingrix vaccine. You need two doses of the vaccine, given 2 to 6 months apart. Another vaccine, Zostavax, may be used in certain cases.


Neuralgia, Postherpetic
Herpes Zoster
Older Adults
Infections
Brain and Nerves
Skin, Hair and Nails
... vaccine, or anyone who might have a weak immune system.Who is at risk for shingles? Anyone who has had chickenpox is at risk for getting shingles. But this risk goes up as you ... with weakened immune systems are at higher risk of getting shingles. ...
HIV/AIDS
National Library of Medicine
AIDS
Acquired Immunodeficiency Syndrome
Human Immunodeficiency Virus
HIV
What is HIV?

HIV stands for human immunodeficiency virus. It harms your immune system by destroying a type of white blood cell that helps your body fight infection. This puts you at risk for serious infections and certain cancers.

What is AIDS?

AIDS stands for acquired immunodeficiency syndrome. It is the final stage of infection with HIV. It happens when the body's immune system is badly damaged because of the virus. Not everyone with HIV develops AIDS.

How does HIV spread?

HIV can spread in different ways:

  • Through unprotected sex with a person with HIV. This is the most common way that it spreads.
  • By sharing drug needles
  • Through contact with the blood of a person with HIV
  • From mother to baby during pregnancy, childbirth, or breastfeeding
Who is at risk for HIV infection?

Anyone can get HIV, but certain groups have a higher risk of getting it:

  • People who have another sexually transmitted disease (STD). Having an STD can increase your risk of getting or spreading HIV.
  • People who inject drugs with shared needles
  • • Gay and bisexual men, especially those who are Black/African American or Hispanic/Latino American
  • People who engage in risky sexual behaviors, such as not using condoms
What are the symptoms of HIV/AIDS?

The first signs of HIV infection may be flu-like symptoms:

  • Fever
  • Chills
  • Rash
  • Night sweats
  • Muscle aches
  • Sore throat
  • Fatigue
  • Swollen lymph nodes
  • Mouth ulcers

These symptoms may come and go within two to four weeks. This stage is called acute HIV infection.

If the infection is not treated, it becomes chronic HIV infection. Often, there are no symptoms during this stage. If it is not treated, eventually the virus will weaken your body's immune system. Then the infection will progress to AIDS. This is the late stage of HIV infection. With AIDS, your immune system is badly damaged. You can get more and more severe infections. These are known as opportunistic infections (OIs).

Some people may not feel sick during the earlier stages of HIV infection. So the only way to know for sure whether you have HIV is to get tested.

How do I know if I have HIV?

A blood test can tell if you have HIV infection. Your health care provider can do the test, or you can use a home testing kit. You can also use the CDC Testing Locator to find free testing sites.

What are the treatments for HIV/AIDS?

There is no cure for HIV infection, but it can be treated with medicines. This is called antiretroviral therapy (ART). ART can make HIV infection a manageable chronic condition. It also reduces the risk of spreading the virus to others.

Most people with HIV live long and healthy lives if they get and stay on ART. It's also important to take care of yourself. Making sure that you have the support you need, living a healthy lifestyle, and getting regular medical care can help you enjoy a better quality of life.

Can HIV/AIDS be prevented?

You can reduce the risk of spreading HIV by:

  • Getting tested for HIV
  • Choosing less risky sexual behaviors. This includes limiting the number of sexual partners you have and using latex condoms every time you have sex. If your or your partner is allergic to latex, you can use polyurethane condoms.
  • Getting tested and treated for sexually transmitted diseases (STDs)
  • Not injecting drugs
  • Talking to your health care provider about medicines to prevent HIV:
    • PrEP (pre-exposure prophylaxis) is for people who don't already have HIV but are at very high risk of getting it. PrEP is daily medicine that can reduce this risk.
    • PEP (post-exposure prophylaxis) is for people who have possibly been exposed to HIV. It is only for emergency situations. PEP must be started within 72 hours after a possible exposure to HIV.

NIH: National Institutes of Health


HIV Infections
Acquired Immunodeficiency Syndrome
Infections
Immune System
... stands for human immunodeficiency virus. It harms your immune system by destroying a type of white blood cell that helps your body fight infection. This puts you at risk for serious ... when the body's immune system is badly damaged because of the virus. ...
Pneumonia
National Library of Medicine
Bronchopneumonia
Walking Pneumonia
What is pneumonia?

Pneumonia is an infection in one or both of the lungs. It causes the air sacs of the lungs to fill up with fluid or pus. It can range from mild to severe, depending on the type of germ causing the infection, your age, and your overall health.

What causes pneumonia?

Bacterial, viral, and fungal infections can cause pneumonia.

Bacteria are the most common cause. Bacterial pneumonia can occur on its own. It can also develop after you've had certain viral infections such as a cold or the flu. Several different types of bacteria can cause pneumonia, including:

  • Streptococcus pneumoniae
  • Legionella pneumophila; this pneumonia is often called Legionnaires' disease
  • Mycoplasma pneumoniae
  • Chlamydia pneumoniae
  • Haemophilus influenzae

Viruses that infect the respiratory tract may cause pneumonia. Viral pneumonia is often mild and goes away on its own within a few weeks. But sometimes it is serious enough that you need to get treatment in a hospital. If you have viral pneumonia, you are at risk of also getting bacterial pneumonia. The different viruses that can cause pneumonia include:

  • Respiratory syncytial virus (RSV)
  • Some common cold and flu viruses
  • SARS-CoV-2, the virus that causes COVID-19

Fungal pneumonia is more common in people who have chronic health problems or weakened immune systems. Some of the types include:

  • Pneumocystis pneumonia (PCP)
  • Coccidioidomycosis, which causes valley fever
  • Histoplasmosis
  • Cryptococcus
Who is at risk for pneumonia?

Anyone can get pneumonia, but certain factors can increase your risk:

  • Age; the risk is higher for children who are age 2 and under and adults age 65 and older
  • Exposure to certain chemicals, pollutants, or toxic fumes
  • Lifestyle habits, such as smoking, heavy alcohol use, and malnourishment
  • Being in a hospital, especially if you are in the ICU. Being sedated and/or on a ventilator raises the risk even more.
  • Having a lung disease
  • Having a weakened immune system
  • Have trouble coughing or swallowing, from a stroke or other condition
  • Recently being sick with a cold or the flu
What are the symptoms of pneumonia?

The symptoms of pneumonia can range from mild to severe and include:

  • Fever
  • Chills
  • Cough, usually with phlegm (a slimy substance from deep in your lungs)
  • Shortness of breath
  • Chest pain when you breathe or cough
  • Nausea and/or vomiting
  • Diarrhea

The symptoms can vary for different groups. Newborns and infants may not show any signs of the infection. Others may vomit and have a fever and cough. They might seem sick, with no energy, or be restless.

Older adults and people who have serious illnesses or weak immune systems may have fewer and milder symptoms. They may even have a lower than normal temperature. Older adults who have pneumonia sometimes have sudden changes in mental awareness.

What other problems can pneumonia cause?

Sometimes pneumonia can cause serious complications such as:

  • Bacteremia, which happens when the bacteria move into the bloodstream. It is serious and can lead to septic shock.
  • Lung abscesses, which are collections of pus in cavities of the lungs
  • Pleural disorders, which are conditions that affect the pleura. The pleura is the tissue that covers the outside of the lungs and lines the inside of your chest cavity.
  • Kidney failure
  • Respiratory failure
How is pneumonia diagnosed?

Sometimes pneumonia can be hard to diagnose. This is because it can cause some of the same symptoms as a cold or the flu. It may take time for you to realize that you have a more serious condition.

Your health care provider may use many tools to make a diagnosis:

  • A medical history, which includes asking about your symptoms
  • A physical exam, including listening to your lungs with a stethoscope
  • Various tests, such as
    • A chest x-ray
    • Blood tests such as a complete blood count (CBC) to see if your immune system is actively fighting an infection
    • A Blood culture to find out whether you have a bacterial infection that has spread to your bloodstream

If you are in the hospital, have serious symptoms, are older, or have other health problems, you may also have more tests, such as:

  • Sputum test, which checks for bacteria in a sample of your sputum (spit) or phlegm (slimy substance from deep in your lungs).
  • Chest CT scan to see how much of your lungs is affected. It may also show if you have complications such as lung abscesses or pleural effusions.
  • Pleural fluid culture, which checks for bacteria in a fluid sample that was taken from the pleural space
  • Pulse oximetry or blood oxygen level test, to check how much oxygen is in your blood
  • Bronchoscopy, a procedure used to look inside your lungs' airways
What are the treatments for pneumonia?

Treatment for pneumonia depends on the type of pneumonia, which germ is causing it, and how severe it is:

  • Antibiotics treat bacterial pneumonia and some types of fungal pneumonia. They do not work for viral pneumonia.
  • In some cases, your provider may prescribe antiviral medicines for viral pneumonia
  • Antifungal medicines treat other types of fungal pneumonia

You may need to be treated in a hospital if your symptoms are severe or if you are at risk for complications. While there, you may get additional treatments. For example, if your blood oxygen level is low, you may receive oxygen therapy.

It may take time to recover from pneumonia. Some people feel better within a week. For other people, it can take a month or more.

Can pneumonia be prevented?

Vaccines can help prevent pneumonia caused by pneumococcal bacteria or the flu virus. Having good hygiene, not smoking, and having a healthy lifestyle may also help prevent pneumonia.

NIH: National Heart, Lung, and Blood Institute


Pneumonia
Infections
Lungs and Breathing
... people who have chronic health problems or weakened immune systems. Some of the types include: Pneumocystis pneumonia (PCP) ... more. Having a lung disease Having a weakened immune system Have trouble coughing or swallowing, from a stroke ...
Skin Infections
National Library of Medicine
Molluscum Contagiosum
What are skin infections?

Your skin is your body's largest organ. It has many different functions, including covering and protecting your body. It helps keep germs out. But sometimes the germs can cause a skin infection. This often happens when there is a break, cut, or wound on your skin. It can also happen when your immune system is weakened, because of another disease or a medical treatment.

Some skin infections cover a small area on the top of your skin. Other infections can go deep into your skin or spread to a larger area.

What causes skin infections?

Skin infections are caused by different kinds of germs. For example,:

  • Bacteria cause cellulitis, impetigo, and staphylococcal (staph) infections
  • Viruses cause shingles, warts, and herpes simplex
  • Fungi cause athlete's foot and yeast infections
  • Parasites cause body lice, head lice, and scabies
Who is at risk for skin infections?

You are at a higher risk for a skin infection if you:

  • Have poor circulation
  • Have diabetes
  • Are older
  • Have an immune system disease, such as HIV/AIDS
  • Have a weakened immune system because of chemotherapy or other medicines that suppress your immune system
  • Have to stay in one position for a long time, such as if you are sick and have to stay in bed for a long time or you are paralyzed
  • Are malnourished
  • Have excessive skinfolds, which can happen if you have obesity
What are the symptoms of skin infections?

The symptoms depend on the type of infection. Some symptoms that are common to many skin infections include rashes, swelling, redness, pain, pus, and itching.

How are skin infections diagnosed?

To diagnose a skin infection, health care providers will do a physical exam and ask about your symptoms. You may have lab tests, such as a skin culture. This is a test to identify what type of infection you have, using a sample from your skin. Your provider may take the sample by swabbing or scraping your skin, or removing a small piece of skin (biopsy). Sometimes providers use other tests, such as blood tests.

How are skin infections treated?

The treatment depends on the type of infection and how serious it is. Some infections will go away on their own. When you do need treatment, it may include a cream or lotion to put on the skin. Other possible treatments include medicines and a procedure to drain pus.


Skin Diseases, Infectious
Infections
Skin, Hair and Nails
... your skin. It can also happen when your immune system is weakened, because of another disease or a ... poor circulation Have diabetes Are older Have an immune system disease, such as HIV/AIDS Have a weakened ...
Pneumocystis Infections
National Library of Medicine

Pneumocystis jirovecii is a tiny fungus that lives in the lungs of many people. Most people's immune systems keep the fungus under control. But if you have a weakened immune system, the fungus can make you very sick.

The most common type of infection is pneumocystis pneumonia (PCP). PCP once was the major cause of death for people with HIV/AIDS. But now, it is possible to prevent or treat most cases. The key to surviving PCP is early treatment. The first signs of PCP are fever, dry cough, shortness of breath, and fatigue. If you have a weakened immune system and have these symptoms, see your doctor right away.

To diagnose PCP, doctors use a microscope to look for the fungus in a sample of lung fluid or tissue. Treatment is with antibiotics.

There is no vaccine to prevent PCP. Some people who are at high risk of getting PCP may need to take antibiotics to prevent it.


Pneumocystis Infections
Infections
Lungs and Breathing
Immune System
... in the lungs of many people. Most people's immune systems keep the fungus under control. But if you have a weakened immune system, the fungus can make you very sick. ...