Novavax (NVX-CoV2373) is a brand-name vaccine that’s prescribed to help prevent COVID-19. As with other drugs, Novavax can cause side effects, such as pain or swelling at the injection site.

Novavax can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Novavax in clinical trialsTrusted Source:

* For more information about this side effect, see “Side effect specifics.”

Mild side effects can occur with Novavax use. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Novavax’s prescribing informationTrusted Source.

Mild side effects that have been reported with Novavax include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews the side effects of the medication. If you develop a side effect while taking Novavax and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics.”

Novavax may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Novavax’s prescribing informationTrusted Source.

If you develop serious side effects while taking Novavax, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported and their symptoms include:

  • cholecystitis (inflammation in the gallbladder), which may include symptoms such as:
    • pain in the right upper abdomen
    • fever
  • fainting after receiving a dose of Novavax
  • heart-related side effects*
  • blood clots*

* For more information about this side effect, see “Side effect specifics.”

ALLERGIC REACTION

For some people, Novavax can cause an allergic reaction.

In general, symptoms of allergic reaction can be mild or serious.

Ways to manage

For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.

For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to X drug [form], your doctor may recommend taking a different medication instead.

Novavax may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

How long do Novavax side effects last?

In most casesTrusted Source, Novavax side effects last a few hours or days. For example, injection site reactions typically go away after a few hours, sometimes lasting a day or two. Fatigue, muscle, or joint pain after receiving Novavax doesn’t typically last more than a few days. (To learn more about Novavax and injection site reactions, see the “Side effect specifics” section.)

Let your doctor or pharmacist know if you develop injection site reactions or other side effects after receiving Novavax that last more than a few days.

Can Novavax cause long-term side effects?

It’s not clear, based on current information. Based on studiesTrusted Source of Novavax, almost all side effects appear to be short term.

Blood clots were very rarely reported in studiesTrusted Source of Novavax. But blood clots also occurred in people who received a placebo in these studies. These reports occurred within 28 days after receiving any dose of Novavax. It currently isn’t clear whether Novavax actually causes blood clots or if they’re due to another factor. (To learn more about Novavax and blood clots, see the “Side effect specifics” section.)

Talk with your doctor or pharmacist if you have additional questions about Novavax and its long-term side effects.

Learn more about some of the side effects that Novavax may cause. To find out how often side effects occurred in clinical trials, see the prescribing informationTrusted Source for Novavax.

Injection site reactions

Injection site reactions are the most common side effect reportedTrusted Source after receiving Novavax. These reactions refer to side effects that happen at or near the site where Novavax is injected. Injection site reactions are possible after receiving any dose of Novavax. But in studies, they were more common after the second dose in the primary series.

Injection site reactions reported with Novavax include:

  • pain
  • skin redness or discoloration
  • swelling
  • tenderness

What you can do

Injection site reactions should go away within a few hours or days after receiving Novavax. Some treatments may help treat your symptoms. For example, you can apply a cold compress to the area to help reduce pain and swelling.

Talk with your doctor or pharmacist if you develop injection site reactions that last more than a few days after receiving Novavax.

Heart-related side effects

Heart-related side effects have been reportedTrusted Source in extremely rare cases after receiving Novavax.

Specifically, myocarditis or pericarditis can occur after receiving Novavax. When these side effects do occur, it’s typically within 1 week after receiving a dose of Novavax. Males between the ages of 12 and 39 years may be at higher risk of these side effects after receiving Novavax. (Sex and gender exist on spectrums. Use of the term “male” in this article refers to sex assigned at birth.)

Although it doesn’t always cause symptoms, myocarditis may sometimes cause symptoms. These symptoms can include:

  • shortness of breath
  • fatigue
  • a sensation of tightness or squeezing in your chest
  • lightheadedness

Symptoms of pericarditis can include:

  • sharp pain in your chest that may decrease if you sit up and lean forward
  • shortness of breath, particularly when you recline
  • a sensation of weakness
  • pain in your shoulder

It’s important to note that viruses, including COVID-19, can also cause myocarditis or pericarditis. (Novavax is prescribed to help prevent COVID-19 infection.) The risk of myocarditis or pericarditis after developing COVID-19 infection appears to be higher than the risk of developing them as a side effect of Novavax.

What you can do

If you’re at risk of myocarditis or pericarditis, your doctor may extend the time between your first and second doses of Novavax to 8 weeks. This may lower your risk.

If you experience chest pain, get immediate medical attention. It’s important for a doctor to rule out a heart attack. Heart attack isn’t an expected side effect of Novavax. But chest pain is a key symptom of a heart attack. It can be difficult to distinguish chest pain caused by pericarditis versus chest pain due to a heart attack.

Let your doctor know if you think you’re experiencing other symptoms of myocarditis or pericarditis after you receive Novavax. They can evaluate your symptoms and determine the best treatment. They can also advise on whether it’s safe for you to receive doses of Novavax or other COVID-19 vaccines in the future.

Blood clots

In studiesTrusted Source involving Novavax, blood clots were reported in extremely rare cases. However, it’s important to note that blood clots also happened in people who received a placebo. Because blood clots were so rare, it currently isn’t known for certain whether these cases were caused by Novavax or other factors. But it’s important to be aware of the symptoms and watch for them after receiving Novavax.

Symptoms of a blood clot can vary depending on where it occurs, but some general ones to watch for include:

  • pain, warmth, or swelling in the affected limb
  • chest pain that worsens when coughing or taking a deep breath
  • shortness of breath
  • a sensation of lightheadedness or faintness

What you can do

If you think you’re having symptoms of a blood clot, get immediate medical attention. If you do have a blood clot, it’s important that it’s treated as soon as possible to prevent complications.

Below is important information you should consider before taking Novavax.

Other precautions

Before taking Novavax, discuss your health history with your doctor. Novavax may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.