COVID-19 vaccine allergic reaction: What to know and who's at risk

Find out what to expect and how to know if your symptoms could be an allergic reaction.

Mercey Livingston CNET Contributor
Mercey Livingston is a health and wellness writer and certified Integrative Nutrition Health Coach. She's written about fitness and wellness for Well+Good, Women's Health, Business Insider, and Prevention.com among others. When not writing, she enjoys reading and trying out workout classes all over New York City.
Mercey Livingston
4 min read
A nurse administers a COVID-19 vaccine to a patient.

Side effects from the vaccine are normal -- but it's important to know the signs of an allergic reaction. 

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The majority of people who get the COVID-19 vaccine will have some mild to moderate side effects as their bodies respond to the vaccine. Some recipients, however, are at a risk of developing an allergic reaction. Health authorities made it very clear that people who have a history of severe allergic reactions might have to hold off on getting vaccinated. For everyone else, the overall risk of allergic reaction is pretty low, but it's important to be prepared for that possibility before your COVID vaccine appointment.

"A CDC analysis reported that in the first month of vaccination (Dec. 14, 2020, to Jan. 13, 2021), the anaphylaxis rate of the COVID-19 vaccinations was 4.5 per million doses, within the range of rates seen with other common vaccines," says Dr. Nicholas Pantaleo, family medicine practitioner and internist at Westmed Medical Group. "Most of these severe allergic reactions occurred within 15 minutes of the vaccine injection." 

An allergic reaction and side effects are two very different things -- and knowing the differences is key to understanding your symptoms. Keep reading below to find out more about how to know if you're experiencing normal side effects from the vaccine or if your symptoms could be something else. 

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Common COVID-19 vaccine side effects

Experiencing side effects after getting a vaccine is completely normal. If you feel sick after getting vaccinated, it doesn't mean that the vaccine made you sick -- it's simply a sign that the vaccine is working and doing its job in your body. "Common side effects from vaccination include pain in the injection site arm with redness and swelling, now known as 'COVID arm.' As the vaccine works, patients can also feel tired, weak, [and have] headaches, muscle pains, chills, fevers and nausea," says Pantaleo. 

Common vaccine side effects:

  • Pain in the injection site arm with redness and swelling
  • Feeling tired/fatigued
  • Weakness
  • Headache
  • Muscle pains
  • Chills
  • Fever
  • Nausea

For most people, the symptoms go away within 48 to 72 hours after being vaccinated, according to Pantaleo. 

Signs of a serious allergic reaction

Most severe allergic reactions happen within 15 minutes of getting vaccinated, which is why when you get a COVID-19 vaccine, you will likely be asked to wait for 15 minutes before leaving in case you experience a reaction. It's important to wait as instructed and report any symptoms to the vaccination staff on site.

The most serious type of allergic reaction is called anaphylaxis, which can cause trouble breathing or cause your throat to close. "If you have a sensation of tightness in the throat or trouble with breathing, the patient should call 911 or go to the nearest emergency room immediately for evaluation. This is treated with epinephrine or an EpiPen," says Pantaleo.

"Non-severe allergic reactions include hives, swelling or wheezing within 4hours of the vaccine," he says. If you experience any of these symptoms and think it's an allergic reaction, you should immediately call your doctor or seek medical expertise to determine what you should do. 

Again, if you're in doubt about whether one of your symptoms is normal or another type of reaction, contact your doctor to discuss your personal circumstances. Additionally, if you have an allergic reaction to the first dose of your vaccine, you likely will not receive the second dose, according to Pantaleo. 

Who's at risk for a COVID-19 vaccine allergic reaction? 

Pantaleo says that the biggest risk factor for potentially having an allergic reaction from a vaccine is if you have a history of allergic reactions or anaphylaxis. "Although no specific vaccine component has been linked to anaphylaxis, a vaccine component called polyethylene glycol (PEG) has been associated with anaphylaxis in other clinical settings. The PEG product is currently found in the mRNA vaccines from Pfizer and Moderna," says Pantaleo. 

If you know that you're allergic to PEG, Johnson & Johnson notes that although the vaccine does not contain PEG, it does have polysorbate, which is a known cross-reactive to PEG. So that means if you are sensitive to PEG, you could also be sensitive to polysorbate in the Johnson & Johnson vaccine. Again, if you're not sure which vaccine might be best for you and your history, talk to your doctor about your options.

Since the vaccines are relatively new, we don't have all of the answers about how and why allergic reactions happen, but we will know more soon. "The NIH (National Institutes of Health) is currently starting a study on COVID-19 vaccine reactions in individuals with a history of allergic reactions. This information can help in the future to determine which patients may be at greater risk of adverse reactions to the COVID-19 vaccines," says Pantaleo.

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The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.