Can You Get the Flu Shot While Sick?

One of the simplest yet most effective ways to avoid sick days and stay out of the doctor’s office every winter is by getting a flu shot. The flu vaccine prevents getting sick from the flu in between 40% and 60% of those who are inoculated when the vaccine is well matched to that year’s viruses, according to the Centers for Disease Control and Prevention. It also helps reduce the length and severity of symptoms in many others who still come down with the infection.

Almost everyone is eligible for a flu shot. The CDC recommends that children younger than 6 months of age (who are too young to get a flu shot) and people with severe, life-threatening allergies to flu vaccine or any ingredient in the vaccine, including gelatin, antibiotics or other ingredients, not get the vaccine. Everyone else, including pregnant women, those with most chronic diseases and those with mild to moderate egg allergies, are either cleared for the vaccine or should talk to their doctor about it.

There is one other caveat, though: if you are already sick with the flu or another illness.

[Read: Who Should Not Get Flu Shots.]

Why Wait to Get a Flu Shot

For most people with mild to moderate symptoms of a cold or the flu, it’s typically OK to proceed with inoculation when you feel sick.

However, “People who have a moderate to severe illness with or without a fever may need to wait until they recover to get vaccinated,” says Dr. Tochi Iroku-Malize, a practicing family physician in Long Island, New York, and a member of the board of directors of the American Academy of Family Physicians. “This is because the immune system is already working to defeat the current illness, and you don’t want to overwhelm the immune system.” If it is already battling one illness, it may not be able to create the antibodies needed to fight off a new illness like the flu. Thus, the vaccine may not be as effective as it would if you were well.

But the wait should be short-lived. “Once symptoms have resolved and your body has returned to a quieter state, the vaccine can be given safely to reactivate your antibodies to combat the flu virus,” says Iroku-Malize, the founding chair and professor of family medicine for the Donald and Barbara Zucker School of Medicine at Hofstra/Northwell in Hempstead, New York, and chair of family medicine for Northwell Health.

Whether you’re experiencing mild to severe symptoms, it’s important to talk to your doctor before getting vaccinated. You may want to call ahead or discuss your options when you arrive for your appointment.

[Read: Flu Shots: What You Need to Know.]

Ask Your Doctor

Even in cases where someone has symptoms like the sniffles, nasal congestion or other signs of an upper respiratory infection, many people can still get the vaccine while feeling under the weather. The main cutoff point typically is having a fever of 101 degrees or higher. “I do not give the flu shot to anyone with a fever, but other than that, if one is in the office with a common cold or other concern, it is the perfect time to get the flu shot as well,” says Dr. Sterling Ransone, a practicing family physician in Deltaville, Virginia, and president-elect of the AAFP. The good news is, most colds don’t cause fever, so a cold shouldn’t prevent you from being inoculated in most cases.

Another reason to avoid a flu shot is if you are immunocompromised, either because of illness or medication. “I don’t give the flu shot if someone is on a short-term round of oral steroids, such as prednisone or methylprednisolone, or has just had a steroid injection,” such as cortisone, Ransone says. “Steroids can suppress the immune system and lead to a lower response to the flu shot. I usually have my patients return to the office for their flu shot about a week after they finish their last steroid dose.”

[Read: Is It COVID-19, Allergies, Flu or a Cold?]

Ransone adds that the shot itself can cause flu-like symptoms. However, these are just symptoms, not the disease. “You cannot get the flu from a flu shot. Period. The flu-like symptoms that you may get after a flu shot is your immune system ramping up to get ready to fight off the flu should you get exposed to it,” he explains. “This really is short-term pain for long-term gain. The possible one to two days of symptoms are much better than risking potentially severe or life-threatening illness.”

If you have any questions or concerns, talk to your family doctor. “Family physicians are well trained to care for people of all ages and in all settings. Preventing the flu is part of what we do,” Iroku-Malize says. “Take the time to discuss with your family doctor how the flu vaccine can help you stay safe.”

More from U.S. News

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