What Are Side Effects of COVID-19 Vaccines?

Before you get the COVID-19 vaccine, you're probably wondering if you'll 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.

It's also important to note that 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, 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.

Here's what else you should know about the side effects of COVID-19 vaccines.

General Information About COVID-19 Vaccines and Side Effects

As of November 2022, the CDC has recommended COVID-19 vaccines for everyone 6 months or older. There are four approved or authorized COVID-19 vaccines in the United States.

The side effects of COVID-19 vaccines tend to be similar to those after other routine vaccinations, and they may last for a few days. Additionally, booster shots produced reactions similar to primary shots.

The CDC recommended that individuals get the Pfizer, Moderna, and Novavax vaccines over Johnson & Johnson vaccines. The Johnson & Johnson vaccine can have rare but serious possible side effects.

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

"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.

Therefore, before you get a COVID-19 vaccine, learn about mild local and general side effects as well as rare serious reactions. Of note, the following signs are for people aged 18 and older, but reactions in children aged 6 months to 17 years aren't too different.

What Are Side Effects of the COVID-19 Vaccines?

Local Side Effects

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

Additionally, you might experience an arm rash, 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.

"COVID arm" 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. However, the reaction is rare.

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.

Whole-Body Side Effects

There are also a number of systemic, or whole-body, side effects from COVID-19 vaccines. Those side effects include:

• Headache
• Fatigue/tiredness
• Muscle pain or swelling
• Fever and/or chills
• Nausea or vomiting

The majority of systemic side effects were mild to moderate for all four vaccines. People were more likely to experience headaches and other systemic side effects after the second dose.

What Are Considered to Be Serious Reactions to COVID-19 Vaccines?

COVID-19 vaccines are considered safe and effective, and severe reactions to them are rare. It's important to be aware of these reactions: Some rare serious reactions that have occurred after COVID-19 vaccines include:

• Anaphylaxis
• Myocarditis
• Pericarditis
• Thrombosis with thrombocytopenia syndrome (TTS)
  
• Guillain-Barré Syndrome (GBS)

Anaphylaxis

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
• Tongue or throat swelling

Anyone experiencing anaphylaxis symptoms requires emergency medical care and/or administration of an EpiPen—an injection used to manage severe allergic reactions.

Of note, a person who has anaphylaxis after their first shot should not get a second dose of the same type of vaccine.

Myocarditis or Pericarditis

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 as well as young males, 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.

Thrombosis With Thrombocytopenia Syndrome and Guillain-Barré Syndrome

The Johnson & Johnson vaccine has been associated with rare cases of 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 Johnson & Johnson 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.

How To Get Relief from Mild or Moderate COVID-19 Vaccine Side Effects

If you end up with the more common side effects of COVID-19 vaccines, there are a few things that can offer relief. One of the main things you can do is to take it easy and resting can help with fatigue and other possible side effects.

If you experience headaches post-vaccination, ask a healthcare provider 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.

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

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 provider about an over-the-counter or prescription nausea remedy.

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

The CDC recommended talking to a healthcare provider 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.

A Quick Review

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 vaccines in the US. Their side effects have typically been mild to moderate and went away within a few days.

For rare, serious reactions or side effects that worsen or don't go away, medical attention is necessary. However, there are ways that can help you get relief from any of the common side effects after a COVID-19 vaccination.

Furthermore, 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).