Getting a flu shot is the best way to protect yourself against influenza A and B. Those are the viruses that cause seasonal flu.

But if you’re sick when your appointment rolls around, ask your provider whether you should postpone the shot until you’re feeling better.

If you have just a minor illness like a cold, you can still get a flu vaccine. If you’re sicker or have a fever, your healthcare provider will likely recommend waiting.

This article explains the potential problems of getting a flu shot when you’re sick, when it’s best to get the vaccine, and why some people should avoid it entirely.

The Risks

Vaccines trigger an immune response in your body. Here’s how it works:

  • The vaccine “shows” your immune system the virus.Your immune system makes antibodies, which are proteins that target and inactivate the virus.Then your body can respond faster when you’re exposed to the flu virus in the future.That quick response can keep you from getting sick.

If you’re sick when you get the vaccine, your immune system is already hard at work fighting the other illness. That means it may not have the resources to develop flu antibodies at the same time. So the vaccine may be less effective at preventing the flu.

The shot could also slow down your recovery from the other illness because your immune system is dividing its resources.

When to Postpone the Flu Shot

Having cold symptoms isn’t necessarily a reason to avoid getting your flu shot. But sometimes it’s better to put it off for a few days.

The Centers for Disease Control and Prevention (CDC) recommends waiting until you’re better if:

  • You have a fever over 101 degrees Fahrenheit
  • You’re very ill
  • You have COVID-19

Fever isn’t a frequent cold symptom in adults. It’s more common in children, though.

If you’re planning to get your child vaccinated and they seem sick, monitor their temperature. If they have a fever, the healthcare provider may decide it’s better to wait than to vaccinate right away.

If you have COVID-19, even if your symptoms are mild, it’s generally recommended that you wait to get your flu vaccine so that you don’t expose medical staff and other people to the virus.

When Not to Wait

The CDC recommends the annual flu vaccine for everyone over the age of 6 months with a few exceptions.

The healthcare provider giving you the vaccine should ask you if you have a fever or are sick before giving it. If they don’t, be sure to speak up.

If you’re not dealing with a moderate to severe illness, you should have no problem with the vaccine and should not hold off. A cough, congestion, headache, and sore throat won’t affect your body’s response to the flu shot.

The nasal spray flu vaccine may be a different story. If you’re congested, you may need to wait until your sinuses clear up. Otherwise, you risk not getting the full benefit of the vaccine.

High-Risk Groups

Certain groups of people are at high risk for flu complications and should be vaccinated if at all possible. If you’re high risk, or you live or care for someone who is, it’s especially important for you to get the vaccine. It’s recommended that people get the vaccine in September or October so that protection lasts throughout the flu season.

High-risk groups include:

  • Babies and young childrenAnyone who’s pregnant or has recently given birthAnyone over age 65People with chronic health conditions, such as heart disease, lung disease, and diabetes

Always speak to a healthcare provider before deciding to cancel a flu shot appointment due to illness. Depending on your risk, the benefits of vaccination may outweigh the concerns.

Who Shouldn’t Get a Flu Shot?

Some people shouldn’t get a flu shot, regardless of whether they’re sick at the time. Be sure to tell your healthcare provider if any of these apply to you or your child:

  • Being under 6 months of age
  • Previous severe allergic reaction to a flu vaccine
  • If you’ve ever had Guillain-Barré syndrome (a condition in which the immune system damages nerves)

In these situations, talk to your healthcare provider about whether the flu vaccine is safe for you.

Summary

Getting a flu shot when you’re sick means dividing your immune system’s focus. That can make the vaccine less effective and keep you sick for longer.

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You don’t need to postpone your flu shot for a mild illness. If you’re at high risk of flu complications, talk to your provider before canceling or putting off your vaccine.

The flu vaccine may not be safe for people with egg allergies or who have had severe reactions to the shot in the past. Talk to a healthcare provider about whether you should be vaccinated.

Frequently Asked Questions

  • Will getting the flu shot when I have a cold make me sicker?
  • No, but it may take longer for you to get over your cold because then your body needs to fight your existing illness and build up antibodies against the flu. If your symptoms are severe, wait until you’ve recovered to get your vaccine.
  • Learn More:
  • How Your Immune System Fights the Common COld
  • Does the flu shot increase the risk of getting COVID-19?
  • No. While one study showed an increased risk, further research found flaws in that study and determined there is no connection between the flu shot and the risk for COVID. The CDC strongly recommends that all eligible people get the flu shot.
  • Can I get the flu shot if I am allergic to eggs?
  • Yes. It’s still recommended that you get the flu shot if you have an egg allergy, but your doctor may recommend that you receive the shot under medical supervision at a hospital. If you’ve ever had an allergic reaction to the flu shot, though, it’s recommended that you do not receive the vaccine again.
  • Learn More:
  • What Is an Egg Allergy?

No, but it may take longer for you to get over your cold because then your body needs to fight your existing illness and build up antibodies against the flu. If your symptoms are severe, wait until you’ve recovered to get your vaccine.

No. While one study showed an increased risk, further research found flaws in that study and determined there is no connection between the flu shot and the risk for COVID. The CDC strongly recommends that all eligible people get the flu shot.

Yes. It’s still recommended that you get the flu shot if you have an egg allergy, but your doctor may recommend that you receive the shot under medical supervision at a hospital. If you’ve ever had an allergic reaction to the flu shot, though, it’s recommended that you do not receive the vaccine again.