Influenza (also known as the flu) is a contagious respiratory illness caused by flu viruses. It is a contagious disease that spreads around the United States every winter, usually between October and May. Anyone can get the flu but the risk of getting the flu is highest among children.
Flu can make some people much sicker than others. These people include young children, people 65 and older, pregnant women, and people with certain health conditions—such as heart, lung or kidney disease, nervous system disorders, or a weakened immune system. Flu vaccination is especially important for these people, and anyone in close contact with them.
Symptoms come on suddenly and may last several days. They can include:
- sore throat
- muscle aches
- runny or stuffy nose
- stomach symptoms, such as nausea, vomiting, and diarrhea (more common in children)
If you are sick with the flu, you may be ill for a week or longer. You should stay home and keep away from others as much as possible, including avoiding travel and not going to work or school, for at least 24 hours after your fever is gone except to get medical care or for other necessities. (Your fever should be gone without the use of fever-reducing medicine.)
If you leave the house to seek medical care, wear a facemask, if available and tolerable, and cover your coughs and sneezes with a tissue. In general, you should avoid contact with other people as much as possible to keep from spreading your illness.
Most people with the flu do not need to see a doctor or go to an emergency department. Most people who get the flu will recover without needing a doctor’s visit, especially people who are generally healthy.
However, you should consult with your healthcare provider if you (or your child) are experiencing any of the following symptoms:
- Fever 101.5 F for three days or more
- Rapidly worsening illness
- Unresponsive and unable to get out of bed
- Bad sore throat
- Difficulty breathing
- Severe cough
- Severe or persistent vomiting
- Chest pain
- Flu-like symptoms improve but then return with fever and worse cough
Vaccination protects against the flu viruses considered most likely to occur this fall and winter. The injectable flu vaccines do not contain any live influenza virus. They are given by injection with a needle, and are often called the "flu shot." Flu vaccine cannot prevent all cases of the flu, but it is the best defense against the disease.
It takes about two weeks for protection to develop after the vaccination, and protection lasts several months to a year. Some illnesses that are not caused by influenza virus are often mistaken for flu. Flu vaccine will not prevent these illnesses. It can only prevent influenza.
Flu vaccination is recommended every year, especially for those who are at increased risk for complications or in contact with people at increased risk. This includes:
- Children younger than five years old. However, the risk for severe complications from seasonal influenza is highest among children younger than two years old.
- Adults 65 years of age or older
- Pregnant women
- Persons with the following conditions:
- Chronic pulmonary (including asthma), cardiovascular (except hypertension), renal, hepatic, hematological (including sickle cell disease), neurologic, neuromuscular or metabolic disorders (including diabetes mellitus)
- Immunosuppression, including that caused by medications or by HIV
- Persons younger than 19 years of age who are receiving long-term aspirin therapy, because of an increased risk for Reye's syndrome
Children and women who are pregnant should see their primary care provider for vaccinations. Adults can receive vaccinations at local pharmacies or from their primary care provider depending on vaccine availability.
Some people should not receive the flu vaccine at all or should receive it using an alternative delivery method. Contact your primary care doctor if you have additional questions or if you meet one of the following criteria:
If you have any severe, life-threatening allergies, including (for example) an allergy to gelatin or antibiotics. If you ever had a life-threatening allergic reaction after a dose of flu vaccine, or have a severe allergy to any part of this vaccine.
If you ever had Guillain-Barré Syndrome (a severe paralyzing illness, also called GBS). Some people with a history of GBS should not get this vaccine. This should be discussed with your doctor.
If you have long-term health problems, such as certain heart, breathing, kidney, liver or nervous system problems, your doctor can help you decide how to proceed.
If you have gotten any other vaccines in the past four weeks, or if you are not feeling well. It is usually okay to receive flu vaccine when you have a mild illness, but you might be advised to wait until you feel better.