Getting your influenza vaccine is the best way to protect yourself against the flu. It’s recommended you get your flu shot as soon as you can, so you have immunity built up before flu season peaks.
But, if you’re sick when it’s time for your flu vaccine appointment, know what’s best for your body and immune system and whether you need to postpone.
The risks of getting your flu vaccine when you’re sick
If you get your flu vaccine while you’re sick, you won’t make yourself sicker. Having a mild cold or illness will not affect the safety or effectiveness of your flu vaccine. But, it may be best to let your body heal from your current illness.
The flu vaccine may slow down your recovery from your current illness because your immune system will have to work harder and is dividing its resources.
When you should postpone
While having common cold symptoms may not be a reason to postpone your flu shot, it may be best wait if:
- You have a fever over 101 degrees Fahrenheit.
- You’re very sick (enough to stay home from work or school).
- You have COVID-19. Even if you have mild symptoms, it’s recommended you wait to get your vaccine so you don’t expose others to the virus.
“Talk to your health care provider about the benefits versus the risks of receiving the flu vaccine when you are sick and illness levels are high,” said Karen Quella, clinical quality nurse specialist with Marshfield Clinic Health System. “Depending on your risk for flu, the benefits may outweigh the concerns.”
When to go ahead with your appointment
If you are dealing with a mild illness or cold, it is OK to move forward with your flu vaccine appointment. Things like a cough, congestion, headache or sore throat won’t affect your body’s ability to make antibodies.
“There is no evidence that acute, or mild illnesses reduce that vaccine’s effectiveness, or that it increases side effects of the vaccine,” Quella said. “However, people with moderate or severe illness usually should not be vaccinated until their symptoms improve.”
It also is OK to get vaccinated if you are taking antibiotics for illness, according to the Centers for Disease Control and Prevention.
Some people are at a higher risk for flu complications and should receive their flu vaccine as soon as possible. Higher-risk individuals include babies or younger children, pregnant women, people age 65 and older and people with chronic health conditions, like heart disease and diabetes.
The flu vaccine may cause side effects that look like the flu
If you notice a reaction after your flu vaccine, that’s a sign your immune system is already working to build protection.
“Common flu vaccine responses include soreness in your arm, headache, nausea, muscle aches or fever,” Quella said.
Flu vaccine reactions usually develop within 24 to 48 hours after getting your vaccine.
“The flu vaccine will not cause the flu. If you get sick following the period that initial reactions may be seen, it’s not due to your vaccine,” she said. “It’s likely due to another illness.”
Learn more about the flu or schedule your vaccine.