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The COVID-19 vaccine is used to prevent COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). If you do get COVID-19, the vaccine can make the illness less severe and help prevent long COVID. There are two different types of vaccines, mRNA vaccines and protein subunit vaccines. While they are not exactly the same, both kinds of vaccines trigger your immune system to create antibodies, helping your body recognize and attack the virus. Common side effects include pain, redness, or swelling near the injection site, tiredness, headache, fever, chills, and muscle and joint pain. 

Uses

What is the COVID-19 vaccine used for?

The COVID-19 vaccine is commonly used to prevent COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It can make the illness less severe if you do get infected. COVID-19 can cause mild to severe illness and even lead to death. COVID symptoms may include fever, chills, cough, shortness of breath, tiredness, muscle and body aches, headache, sore throat, stuffy or runny nose, nausea, vomiting, and diarrhea. It can also cause a new loss of taste and/or smell.

Staying current on COVID-19 vaccinations lowers the risk of severe illness, hospitalization, and death. It may also help prevent long COVID, where symptoms last at least three months. 

How does the COVID-19 vaccine work (mechanism of action)?

There are two types of COVID-19 vaccines: mRNA vaccines and protein subunit vaccines. Both types of vaccines work by triggering your immune system to make antibodies to recognize and fight the virus that causes COVID-19. This can help prevent you from getting sick and make the illness less severe.

How should I store the COVID-19 vaccine?

The COVID-19 vaccine is usually given by a pharmacist or other health care provider in a pharmacy, hospital, or clinic. You will not store it at home.

Side Effects

What are the most common side effects of the COVID-19 vaccine?

The most common side effects of the COVID-19 vaccine are listed below. Side effects may vary depending on the product used. Tell your health care provider if you have any of these side effects that bother you.

  • Pain, redness, or swelling near the injection site
  • Tiredness
  • Headache
  • Fever
  • Chills
  • Muscle pain
  • Joint pain
  • Swelling and tenderness in the armpits
  • Irritability, crying, poor feeding (in infants and small children)

There may be other side effects of COVID-19 vaccines that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of the COVID-19 vaccine?

While less common, the most serious side effects of the COVID-19 vaccine are described below, along with what to do if they happen.

Severe Allergic Reactions. A COVID-19 vaccine may cause allergic reactions, which can be serious. Get emergency help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Myocarditis and Pericarditis. While rare, COVID-19 vaccines may cause inflammation of the heart (myocarditis) or the surrounding lining (pericarditis). The risk for this is highest in the first week after vaccination. Contact your health care right away if you have chest pain, shortness of breath, or trouble breathing.

Warnings & Precautions

Who should not use the COVID-19 vaccine?

Allergies to Ingredients. People who are allergic to any of the following should not receive the COVID-19 vaccine.

  • Comirnaty
  • Moderna COVID-19 Vaccine
  • Novavax COVID-19 Vaccine
  • Pfizer-BioNTech COVID-19 Vaccine
  • Spikevax
  • Any of the ingredients in the specific product received

Your pharmacist or other health care provider can tell you all of the ingredients in the specific COVID-19 vaccine products they stock.

What should I know about the COVID-19 vaccine before using it?

Your health care provider will recommend a COVID-19 vaccine and schedule. It is important to follow the schedule recommended by your health care provider. If you have questions or concerns about which vaccine you should get, ask your health care provider.

Your risk of dizziness or fainting, which may lead to a fall, is the highest within a few minutes after receiving the vaccine. Your health care provider may want to watch you for this time to ensure your safety.

You can get a COVID-19 vaccine at the same time as other vaccines.

The COVID-19 vaccine will not give you COVID-19. Not everyone who receives the vaccine will be fully protected.

What should I tell my health care provider before using a COVID-19 vaccine?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if the COVID-19 vaccine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • An allergic reaction to any vaccine
  • Received any other COVID-19 vaccine
  • A previous allergic reaction to any COVID-19 vaccine
  • A reaction to any previous vaccine, including fainting or Guillain-Barré syndrome
  • Fever or recent illness
  • Heart problems, including myocarditis or pericarditis
  • A weak immune system, get infections easily, or take medicines or treatments that suppress the immune system (such as radiation or chemotherapy)
  • Multisystem inflammatory syndrome (MIS-C in children and MIS-A in adults)
  • Bleeding disorder or take a blood thinner medicine

Pregnancy. It is not known if or how the COVID-19 vaccine could affect pregnancy or harm a fetus. Tell your health care provider if you are or plan to become pregnant. 

Breastfeeding. It is not known if the COVID-19 vaccine passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should receive the COVID-19 vaccine while breastfeeding.

Interactions

Does the COVID-19 vaccine interact with foods or drinks?

There are no known interactions between the COVID-19 vaccine and foods or drinks.

It is unknown if drinking alcohol will affect the COVID-19 vaccine.

Does the COVID-19 vaccine interact with other medicines (drug interactions)?

There are no known interactions between the COVID-19 vaccine and other medicines. Always tell your health care provider about all recent and upcoming vaccines, any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. 

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much COVID-19 vaccine?

If you or someone else has used too much COVID-19 vaccine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of the COVID-19 vaccine?

If you miss an appointment for your COVID-19 vaccine, call to make another appointment as soon as possible. It is important to follow the vaccine schedule recommended by your health care provider.