COVID-19 Vaccine Side Effects: What You Might Experience After You Get Your Shot

Side effects are typically mild or moderate and do no lasting damage.

Before you get the COVID-19 vaccine, you're probably wondering if you're going to experience vaccine side effects, what they'll feel like, and if they will be severe.

While it's impossible to know ahead of time if you'll have vaccine side effects, rest assured they're totally normal, as well as typically mild to moderate and short-lived, per the Centers for Disease Control and Prevention (CDC).

As of July 2022, two vaccines had been approved by the US Food & Drug Administration (FDA) for use in the US: Pfizer and Moderna. Two more had been authorized by the FDA, including Johnson & Johnson (J&J) and Novavax, per the CDC. The CDC recommended COVID-19 vaccines for everyone 6 months or older.

Between December 14, 2020–August 18, 2022, more than 607 million doses of COVID-19 vaccines were administered in the US, with 79% of the US population receiving at least one dose, per the CDC. The vaccines were shown to be safe and effective, according to the CDC.

The side effects of COVID-19 vaccines tend to be similar to those after other routine vaccinations, per the CDC. For Pfizer, Moderna, and Novavax vaccines, the CDC said that side effects are "common but are mostly mild," although "some people have reactions that affect their ability to do daily activities."

Side effects may last for a few days. The CDC noted that the booster shots produced reactions similar to primary shots.

The Pfizer, Moderna, and Novavax vaccines were preferred by the CDC over the J&J vaccine because of the J&J vaccine's rare but serious possible side effects.

Design by Jo Imperio

Having side effects may actually be a good thing. Some, such as fever, swollen lymph nodes, and chills, are signs that the vaccine has triggered your body to build protection against COVID-19.

"The bigger your body's immune response, the more likely you're going to feel like you have a flu-like illness," Kathleen Mullane, DO, PharmD, professor of medicine and director of infectious disease clinical trials at the University of Chicago, told Health. But side effects aren't necessary for your body to build enough immunity, per the CDC.

Before you get a COVID-19 vaccine, learn about mild local and general side effects and rare serious reactions. The signs listed here are for adults (people older than 18), but reactions in children aged 6 months to 17 years aren't too different, per the CDC.

Local Side Effects

Pain at the Injection Site

You may experience pain, redness, and swelling where you got the shot, per the CDC. For all four vaccines, pain at the injection site was the most common symptom, per the CDC.

About 85% of people over age 18 in studies who received the Pfizer vaccine reported at least one local symptom, per the CDC. More than 80% experienced local symptoms after the Moderna vaccine, per the CDC.

Arm Rash

This side effect is also known as the "COVID arm." It can occur from a few days to more than a week after you get the vaccine. The rash is "red, itchy, swollen, or painful" and sometimes large, per the CDC.

"COVID arm" is rare. It may be a sign of a hypersensitivity reaction (similar to an allergic reaction), but it doesn't prevent you from getting your next dose of the vaccine, if necessary, per a July 2021 paper published in the Indonesian Journal of Internal Medicine. The rash will resolve on its own.

If you develop "COVID arm," you can take an antihistamine (allergy medication) to quell itching or take acetaminophen for the pain. Once the rash goes away, and it's time for your second dose, consider switching arms, the CDC advised.

Whole-Body Side Effects


Headaches were one of the most common systemic (whole-body) side effects of all four vaccines, along with fatigue and (with the exception of J&J) muscle pain. The majority of systemic side effects were mild to moderate for all four vaccines, per CDC data. People were more likely to experience headaches and other systemic side effects after the second dose.

About 42% of people aged 18–55 experienced headaches after the first dose of the Pfizer vaccine, compared to about 25% of people over age 55, per the CDC.

About 35% of people aged 18–64 who got the Moderna vaccine had headaches. People over age 64 were slightly less likely to experience this symptom, per the CDC.

If you experience headaches post-vaccination, ask a healthcare professional if you can take over-the-counter pain relievers such as ibuprofen, acetaminophen, or (if you're older than 18) aspirin. You should avoid these medications for pain prevention before the vaccine, per the CDC.


Fatigue can also happen after any COVID-19 dose. Overall, more than 19% of adults experienced this side effect for each vaccine, per the CDC. Adults between the ages of 18–55 who got the first dose of the Pfizer vaccine were most likely to get fatigued—almost half of them experienced this symptom, per the CDC.

Taking it easy and resting can help with fatigue and other possible side effects, per the CDC.

Muscle Pain

COVID-19 itself can leave people with muscle aches, and so can the COVID-19 vaccine. New or worsened muscle pain (also called myalgia) was reported for all four vaccines, but, for most people, the pain didn't prevent them from daily activities. In Pfizer trials, most participants experienced mild or moderate pain, per the CDC.

You may also experience joint stiffness (also called arthralgia) after the Moderna vaccine, per the CDC. Joint pain was reported after the Pfizer and Novavax vaccines, per the CDC.

Fever and/or Chills

This side effect is the result of your immune system's activation—it can make you feel terrible, but it's normal. For some vaccines, getting a fever is rare—as low as three in 1,000 people over age 64 had a fever after the first dose of the Moderna vaccine, per the CDC. Adults who got the first dose of the Pfizer vaccine got a fever in fewer than 4% of cases, per the CDC.

The CDC recommended drinking lots of fluids and dressing lightly to help with fever discomfort. You can also talk to a healthcare professional about taking an over-the-counter fever reducer such as aspirin or acetaminophen.

Nausea and/or Vomiting

About 9% of people aged 18–64 in the clinical trials for the Moderna vaccine reported nausea and/or vomiting after receiving their first dose, per the CDC. As with other symptoms, nausea was more likely to show up after the second dose—the rate of people aged 18–64 who got nauseated more than doubled after the second dose.

People over 64 years old were about half as likely to report nausea and/or vomiting after the Moderna vaccine. Nausea was not a reaction reported in the Pfizer trials, per the CDC.

If you do feel nauseated after any vaccine, consider resting and eating light or bland foods if you're hungry. If the side effect is severe, talk to a healthcare professional about an over-the-counter or prescription nausea remedy.

Rare Serious Reactions

COVID-19 vaccines are considered safe and effective and severe reactions to them are rare. Still, it's important to be aware of them. And make sure to stay at your vaccination site for at least 15 minutes after you get the shot (30 minutes if you've had a severe allergic reaction before), per the CDC.

Here are some rare serious reactions that have occurred after COVID-19 vaccines, per the CDC.

Anaphylaxis is a severe allergic reaction that has only been documented in about five cases per one million vaccine doses. It usually happens within 30 minutes of vaccination. Symptoms of anaphylaxis include trouble breathing, wheezing, hives or rashes, and tongue or throat swelling, per the CDC.

Anyone experiencing anaphylaxis symptoms requires emergency medical care and/or administration of an EpiPen—an injection used to manage severe allergic reactions, per the CDC. A person who has anaphylaxis after their first shot should not get a second dose of the same type of vaccine.

You may also have a "small but increased" risk of myocarditis (heart muscle inflammation) or pericarditis (inflammation of the heart's outer lining). People between the ages of 12–24 are at the highest risk, though this complication is still rare and under investigation by the CDC, as of July 2022. Most people with post-vaccine myocarditis or pericarditis recovered quickly with medication.

The J&J vaccine has been associated with rare cases of thrombosis with thrombocytopenia syndrome (TTS) and Guillain-Barré Syndrome (GBS). TTS is a blood clotting condition, and GBS is a condition that can cause muscle weakness and potentially paralysis. In May 2022, the FDA limited J&J vaccine use to only adults (people 18 or older) who couldn't access or medically tolerate other vaccines, or those who couldn't receive other vaccines.

When You May Experience Side Effects

You may experience side effects within the first seven days, for a few days, per the CDC. For the Pfizer, Moderna, and Novavax vaccines, some side effects are more common after the second dose, per the CDC.

"The second dose helps create a more sustained antibody response," William A Petri, MD, PhD, chief of the division of infectious diseases and international health at UVA Health in Charlottesville, Virginia, told Health.

In clinical trials for the Moderna and Pfizer vaccines, people who experienced whole-body symptoms such as headaches or fatigue felt them within one to two days of getting the vaccine, for about one to two days, per the CDC.

What To Do if Your Side Effects Don't Go Away or Get Worse

The CDC recommended talking to a healthcare professional if you experience the following after the vaccine:

  • Pain or redness where you got the shot gets worse after 24 hours
  • The side effects don't go away after a few days
  • You're worried about the side effects you're experiencing

If you show any of the signs of anaphylaxis, that's a medical emergency—call 911, the CDC warned.

Overall, vaccines are a safe and effective way to protect yourself and the people around you from COVID-19. Millions of people have gotten COVID-19 in the US. Their side effects have typically been mild to moderate and went away within a few days, per the CDC.

If you feel any side effects, do your part to contribute to ongoing research by reporting them through v-safe—a smartphone-based tool you can use to quickly and confidentially report your symptoms—or the Vaccine Adverse Event Reporting System (VAERS).

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.

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