What You Need to Know About the Flu Shot

Indications, Timing, and More

In This Article

Each year, public health officials and healthcare providers encourage people to get vaccinated against influenza (the flu). While flu shots are not appropriate for everyone, they are for most people. Getting one—and doing so in a timely manner—cannot only protect your health, but the health of everyone you come in contact with.

Who Should Get a Flu Shot

The Centers for Disease Control and Prevention (CDC) says everyone over 6 months old should get one. It's even more important if you're at high risk for serious complications from the flu; if you have frequent exposure to the general public (healthcare workers, emergency personnel, etc.), or if you are a caregiver in close contact with high-risk individuals.

For seasonal flu, high-risk groups include:

  • Children aged 2 and younger
  • Adults over age 65
  • People living in a long-term care facility
  • People with weakened immune systems
  • Pregnant women or those who gave birth in the past two weeks

People with chronic health conditions are also considered high risk. Conditions and circumstances that are known to increase your risk of serious flu complications include:

  • Asthma
  • Neurological/neurodevelopmental conditions
  • Blood disorders, including sickle cell disease
  • Chronic lung disease, including cystic fibrosis and chronic obstructive pulmonary disease (COPD)
  • Endocrine disorders, including diabetes
  • Heart disease
  • Kidney or liver disorders
  • Metabolic disorders
  • Obesity
  • Anyone with a weakened or suppressed immune system due to illness or medication
  • People under 19 who are on long-term salicylate-containing medications, including aspirin

Who Shouldn't Get a Flu Shot

The flu vaccine is not right for everyone. You should not get a flu shot if you have:

  • Fever or moderate to severe illness at the time of vaccination
  • History of previous severe or life-threatening allergic reaction to a flu shot

Infants under 6 months old should also not receive the flu shot. Additionally, if you have a history of Guillain-Barré syndrome after previous flu vaccinations, talk to your healthcare provider before getting a flu shot again.

Egg Allergy: Important Changes

If you have an egg allergy, talk to your healthcare provider about whether the flu shot is right for you. Egg allergies used to be a reason to avoid flu shots, but newer research has indicated that even people with severe egg allergies may be able to safely get the flu vaccine under proper supervision.

Some flu vaccines are now available that aren't grown in eggs, so the threat of a reaction for people with egg allergies is eliminated.

When You Should Get Vaccinated

The seasonal flu vaccine is different every year. The formula is based on what experts believe are the strains most likely to cause illness the following season. Therefore, it is important to get a flu shot every year.

The flu shot takes two weeks to become effective after it is given, so it's best not to wait until people around you start getting the flu before you're vaccinated.

If you're at high risk for the flu and related complications, you should get your vaccine as soon as they are available.

Seasonal flu shots generally become available in the fall, between September and November.

Some people think that if they get the flu, there's no reason to get the flu vaccine. However, that's not the safest approach. Typically, multiple strains of the influenza virus go around each year. While the flu vaccine can protect against three strains of flu (trivalent) or four strains (quadrivalent), just because you get a strain of influenza A in December doesn't mean you can't get a different strain of influenza B later in the season.

Is It Ever Too Late?

Flu vaccines are typically given in the early fall through March or April. CDC recommends getting a flu shot by the end of October. However, as long as the influenza virus is making people sick in your community, it's worth getting vaccinated against it. It won't provide full protection immediately, but it could still prevent you from getting sick.

Where to Get a Flu Shot

You have many options for where to get a flu shot, including:

  • Your doctor's office
  • Pharmacies
  • Walk-in clinics
  • Grocery store clinics
  • Hospitals
  • Local health department
  • Flu clinics (Use CDC's Flu Clinic Locator for locations.)

Many employers and schools often offer flu shots on-site during special vaccination events as well.

If you have significant health issues or an egg allergy, your doctor's office is the best place to get your flu shot. Your doctor should know your medical history and will know if there is any reason you should not have a flu vaccine or if one type is better for you than another. They can also monitor for adverse reactions, if necessary.

Administration of the Vaccine

In adults, the flu vaccine is typically injected into an arm muscle. However, the vaccine is also available in several forms for which administration differs:

  • In children, it's generally given as a shot in the upper arm or thigh.
  • It's also available as a nasal spray vaccine; however, the inhaled form is not for use in children under 2 years old, pregnant people, adults over 49, people with weakened immune systems, or anyone age 2 to 4 with asthma. There is a precaution for those age 5 and up who have asthma, but this doesn't mean the vaccine is contraindicated for this group. Talk to your healthcare provider if you have asthma.
  • The Fluzone intradermal flu vaccine is available and is administered using a much smaller needle than the traditional flu shot.
  • A high-dose vaccine is available for older adults age 65 and up.

Talk to your healthcare provider to determine what type of vaccination is available in your area and which one is right for you. 

Side Effects

Most flu vaccine side effects are minor. Some of the more common side effects include:

  • Low-grade fever
  • Soreness at the injection site
  • Decreased energy

Contrary to rumor, you cannot get the flu from the flu shot.

Contact your doctor immediately or go to the emergency room if you experience:

  • Severe swelling
  • Difficulty breathing
  • Numbness

These are signs of allergy or serious complications and could be fatal.

A Word From Verywell

Nearly everyone should get a seasonal flu vaccine. It's important for preventing the flu in yourself and others. Although flu shots aren't perfect and won't always prevent illness completely, those who are vaccinated have significantly milder symptoms if infected and are less likely to be hospitalized or have serious complications as a result of the virus.

If you aren't sure about whether or not the flu vaccine is right for you or your family, talk to your healthcare provider.

Was this page helpful?
Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. People at High Risk For Flu Complications. Updated August 27, 2018.

  2. Centers for Disease Control and Prevention. Who Should and Who Should NOT get a Flu Vaccine. Updated October 11, 2019.

  3. Centers for Disease Control and Prevention. Live Attenuated Influenza Vaccine [LAIV] (The Nasal Spray Flu Vaccine). Updated November 7, 2019.

  4. Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep. 2016;65(5):1-54. doi:10.15585/mmwr.rr6505a1