Our immune system is unique, so people react differently to coronavirus vaccines.
The side effects you may experience after receiving an injection may depend on broad categories such as age and gender, as well as more individual characteristics such as genes or history of exposure to infections.
In general, medical experts say it’s normal for you to feel uncomfortable for up to 48 hours after your injection. This is usually a sign that the vaccine is working.
Common side effects include injection site pain, fatigue, and headache. For those getting the Pfizer or Moderna injections, people also feel more exhausted after their second dose.
“That feeling of boredom and fatigue and fever causes your body to have a great immune response,” said Dr. Sharon Nachman, chief of pediatric infectious diseases at Stony Brook Children’s Hospital, to Insider.
But there are ways to minimize discomfort, experts said. Here are some tips to manage the side effects of your vaccine.
If possible, try to avoid painkillers
The Centers for Disease Control and Prevention do not recommend taking any pain relievers before your vaccination. That’s because medications like Tylenol, Advil, or Aleve lower your immune response when you rely on your body to do the opposite.
If you need to take a pain reliever after your injection, Nachman said Tylenol is the least likely to interfere with your immune response.
“Right after the vaccine, I’d rather you didn’t take anything,” she said. “But the next day if you feel like you need to take something, I’d rather you take some Tylenol.”
Experts generally recommend trying some natural pain relief methods first.
Remedies for sore arms: ice and exercise
A COVID-19 injection.
Getty / David Greedy
Once a vaccine gets into your arm, blood flow increases and immune cells hit the site. This can result in injection site pain – the most common side effect of all three US-authorized coronavirus vaccines.
The CDC recommends applying a clean, cool washcloth over the area where you received your injection to reduce pain. An ice park also operates, Dr. Lipi Roy, an internal medicine physician in New York City, wrote on Twitter.
Experts also recommended moving your vaccinated arm to stimulate blood flow.
“By moving the arm, it helps that local area of inflammation spread more quickly,” said Dr. Daniel Summers, a pediatrician in Maine, recently told Insider.
But don’t massage the vaccine site with your hand, he said – that could worsen inflammation and pain.
Hot showers can help with muscle pain
Muscle pain is one of the most common side effects of vaccines. About 60% of the Moderna clinical trial participants, 38% of the Pfizer participants, and one-third of the Johnson & Johnson participants reported the symptom.
Some doctors recommend Epsom salt baths to relieve muscle or body aches, but Nachman is an even simpler remedy.
“I’m basically just telling people to take a nice hot shower,” she said. “It’s accessible to everyone and relatively cheap, and most people feel better afterwards.”
Check your tongue for signs of dehydration
Experts suggested drinking plenty of fluids before and after you get your injection. Side effects such as fever and nausea can dry you out. Or, if you’re already dehydrated, that could worsen your side effects as well.
Nachman said there is an easy trick to determining if you should drink more water.
“If you put your tongue in the mirror and your tongue is white, you are not hydrated,” she said.
Keep the exercise light
A man wears a face mask while exercising.
Roberto Serra / Iguana Press / Getty Images
Exercising after your admission isn’t necessarily a bad idea – if you feel like it.
Still, experts suggested not straining yourself beyond your normal activity level. Even if you’re used to exercise a lot, Nachman said, it’s important to listen to your body.
“If you’re used to a 40-mile bike ride, this may not be the day,” she said. “If your body says, ‘I can’t roll out of bed,’ don’t force yourself to run on the treadmill or ride the bike. Take it easy for the day.”
Plan to take time off from work after your second dose
A recent CDC report examined side effects in more than 1.9 million Americans who had received both doses of Pfizer or Moderna vaccines. Overall, side effects were more numerous and severe after the second dose of both vaccines.
The only exception is if you had COVID-19 sooner: A small study from the Icahn School of Medicine at Mount Sinai found that side effects from vaccines such as fatigue, headache, and chills were more common after the first dose in people with pre-existing immunity against the coronavirus than among people who have never been infected.
In any case, medical experts said, plan to take time off from work if you feel exhausted.
“Take sick day because you will be less effective at the work you do,” Nachman said.
Call a doctor if side effects persist after a few days
A person will receive the AstraZeneca vaccine in Bologna, Italy on March 19, 2021.
Michele Lapini / Getty Images
The CDC recommends calling a doctor if redness or tenderness at the injection site gets worse after 24 hours.
Nachman said she has also seen some patients develop a rash that takes a week or so to clear. The reaction is more common after Moderna’s vaccine than Pfizer’s, she said. (Nachman said she hasn’t seen enough patients who have received the J&J vaccine to know if a rash is common after that injection.)
Usually, a rash isn’t a cause for concern, she added – unless you get a fever, too.
“We see local redness. We certainly see local tenderness. We also see a little rash. But a combination of those with a fever? That would be a trigger to get someone else to look,” Nachman said.
The CDC also recommends calling a doctor if your side effects don’t go away after a few days. In most cases, however, side effects are a welcome response.
“Remember, that’s your immune system kicking in,” Nachman said. ‘You have done an excellent job immunologically. We are happy.’
Julia Naftulin contributed to the reporting.