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Flu Shot (Vaccine) for Adults

Medically reviewed by Drugs.com. Last updated on May 2, 2022.

What is the flu shot?

The flu shot is a vaccine given in your upper arm or thigh to help prevent influenza (the flu). The flu is caused by a virus. The virus spreads from person to person through coughing and sneezing. Several types of viruses cause the flu. The viruses change over time, so new vaccines are made each year. The vaccine begins to protect you about 2 weeks after you get it. Get the vaccine as soon as it is available.

What should I tell my doctor before I get a flu shot?

  • You have any serious allergies, such as an egg allergy that causes a severe reaction. The flu vaccine may contain a small amount of egg protein. The amount is so low that it is not likely to cause an allergic reaction. Egg-free vaccines may be available.
  • You developed Guillain-Barré syndrome within 6 weeks of getting a flu shot. You may not be able to get any flu vaccine unless your provider feels the benefits outweigh the risks.

Who should not get the flu shot or should wait to get it?

You may need to wait to get the flu shot, or instead get the nasal flu vaccine. Tell your healthcare provider if:

  • You had an allergic reaction to a flu shot or any part of it.
  • You are sick or have a fever of 101°F (38.3°C) or higher.

What are the risks of the flu shot?

The vaccine may cause mild symptoms, such as a fever, headache, and muscle aches. You may also have mild to moderate soreness or redness at the area where you were given the shot. You may still get the flu after you receive the vaccine. You may have an allergic reaction to the vaccine. This can be life-threatening.

Treatment options

The following list of medications are in some way related to or used in the treatment of this condition.

Call your local emergency number (911 in the US) if:

  • Your mouth and throat are swollen.
  • You are wheezing or having trouble breathing.
  • You have chest pain or your heart is beating faster than normal for you.
  • You feel like you are going to faint.

When should I seek immediate care?

  • Your face is red or swollen.
  • You have hives that spread over your body.

When should I call my doctor?

  • You feel weak or dizzy.
  • You have increased pain, redness, or swelling around the area where the shot was given.
  • You have questions or concerns about the flu shot.

Care Agreement

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your healthcare providers to decide what care you want to receive. You always have the right to refuse treatment. The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.