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Protect Yourself from Seasonal Flu

The Basics
Overview
Everyone age 6 months and older needs to get a flu vaccine every year. Seasonal flu vaccines are the best way to protect yourself and others from the flu.
For many people, seasonal flu is a mild illness. But sometimes, the flu can be serious or even deadly. The flu:
- Is linked to serious infections like pneumonia
- Can make existing health problems worse (for example, long-term heart or lung disease)
- Can lead to hospitalization or death
Flu vaccines can help prevent people from getting sick with the flu — and lower the risk of hospitalization and death for people who do get sick.
The flu spreads easily from person to person. So when you get a flu vaccine, you don’t just protect yourself. You also can help protect everyone around you.
When do I need to get a seasonal flu vaccine?
Most people should get a flu vaccine in September or October each year. After you get vaccinated, it takes about 2 weeks for your body to develop protection against the flu. That’s why it’s a good idea to get a flu vaccine before flu starts to spread in your community.
Even if you don’t get a flu vaccine by the end of October, getting a vaccine later can still protect you from the flu. Keep in mind that flu season can last as late as May or June.
Flu Symptoms
What is the flu?
The flu is caused by viruses that can infect your nose, throat, and lungs. Experts think it mainly spreads from person to person when someone with the flu coughs, sneezes, or talks. It's also possible to get sick with the flu by touching a surface or object that has flu virus on it and then touching your mouth, nose, or eyes.
Signs and symptoms of the flu can include:
- Cough
- Sore throat
- Headache
- Feeling tired
- Runny or stuffy nose
- Muscle or body aches
- Fever or feeling feverish
- Having chills
For some people, the flu may also cause vomiting (throwing up) and diarrhea (frequent, watery poop). This is more common in children than adults.
Keep in mind that not everyone with the flu gets a fever.
Flu Vaccines
How are flu vaccines given?
You can get a flu vaccine as a shot or as a nasal spray.
Are there any side effects from seasonal flu vaccines?
Flu vaccines can cause side effects, but they're usually mild. They usually start soon after you get the vaccine and last for 1 to 2 days.
Side effects from the flu shot can include:
- Soreness, redness, or swelling where you got the shot
- Headache
- Fever
- Nausea (feeling sick to your stomach)
- Body aches
Side effects from the nasal spray vaccine may include:
- Runny nose
- Cough
- Headache
- Sore throat
These side effects aren’t the flu. You can’t get the flu from flu vaccines.
Am I at Higher Risk?
Am I at higher risk for serious complications from the flu?
For some people, the flu is more likely to cause serious illness that can lead to hospitalization or even death.
People at higher risk for serious flu complications include:
- Children younger than 5 years — and especially children younger than 2 years
- Women who are pregnant or have had a baby in the last 2 weeks
- Adults age 65 years and older
- People with some long-term health conditions (like asthma, diabetes, or heart disease)
- People with a weakened immune system (like people with HIV)
- People who live in long-term care facilities (like nursing homes)
- People from certain racial and ethnic groups, including people who are African American, Hispanic or Latino, and American Indian or Alaska Native
- People with obesity who have a body mass index (BMI) of 40 or higher
If you’re at higher risk for serious flu complications, it’s especially important to get a flu vaccine before the flu starts to spread in your community. And if you care for, or spend time with, someone at higher risk for serious flu complications, a flu vaccine can help protect you both.
Flu Medicine
Is there medicine that can treat the flu?
Yes. If you get sick with the flu, your doctor may prescribe medicines called flu antiviral drugs. Flu antiviral drugs can help shorten the time that you’re sick. They can also help prevent serious flu complications.
If you’re at higher risk for serious flu complications and you get flu symptoms, tell your doctor right away.
Flu antiviral drugs work best if you start taking them in the first 2 days after you get sick. But they may still help if you take them later on, especially if you’re very sick.
Content last updated March 4, 2025