Your head aches, and so does every muscle in your body. You're cold one minute and hot the next. Your throat is scratchy and you're starting to cough. You might be coming down with the flu!

Flu Season Is October to May

If you get the flu, you'll have lots of company. Each year from October to May, millions of people all across the United States come down with the flu. Kids get the flu most often. But people in every age group — including teens — can catch it.

What Is the Flu?

Flu is the common name for influenza. It's a virus that infects the respiratory system.

Often when you're sick with a virus, your body builds up a defense system by making antibodies against it. That means you usually don't get that particular virus strain again. Unfortunately, flu viruses mutate (change) each year. So you aren't protected from getting the flu forever.

Some years the change in the flu virus is slight. So if you do get the flu, it's mild. The antibodies from having the flu before give you partial protection. But every 10 years or so the flu virus goes through a major change and many people get severe cases. These large-scale outbreaks are called epidemics. If they spread worldwide, they're called pandemics. The H1N1 ("swine flu") outbreak of 2009-2010 was considered a pandemic.

How Does the Flu Spread?

The flu virus spreads through the air when a person who has the virus sneezes, coughs, or speaks. The flu can sometimes be passed on through objects that someone with the virus touched, sneezed, or coughed on. When a healthy person touches these contaminated items and then touches his or her mouth or nose, the virus can enter their system.

People carrying the virus can be contagious 1 day before their symptoms appear and about 5 to 7 days after they first get symptoms. So it's possible to pass the flu on before you even know you're sick.

Flu epidemics often start in schools and then move quickly through a community as students spread the virus to family members and people around them.

How Do I Know if I Have the Flu?

Flu symptoms appear anywhere from 1 to 4 days after a person has been exposed to the virus. The main symptoms of flu are:

• headache
• sore throat
• fever
• chills
• muscle aches
• stuffy nose
• dry cough

Someone with the flu may have a high fever — for example, that person's temperature may be around 104°F (40°C). People with the flu often feel achy and extra tired. They may lose their appetites.

The fever and aches usually disappear within a few days, but the sore throat, cough, stuffy nose, and tiredness may continue for a week or more. In addition, the flu can sometimes cause vomiting, abdominal pain, and diarrhea.

If you have only vomiting and diarrhea without the other flu symptoms, you probably have . Though some kinds of gastroenteritis are known as "stomach flu," they're not the same as seasonal flu. Some gastrointestinal infections are caused by non-flu viruses or bacteria.

Although you may feel miserable if you get the flu, it's unlikely to be serious. It's rare that healthy teens have complications from the flu. Older adults (over age 65), young kids (under age 5), and people with chronic medical conditions are more likely to become seriously ill with the flu.

What to Do If the Flu Bugs You

If you get the flu, the best way to take care of yourself is to rest in bed and drink lots of liquids like water and other non-caffeinated drinks. Stay home from school until you feel better and your temperature has returned to normal.

Most people who get the flu get better on their own after the virus runs its course. But call your doctor if you have the flu and any of these things happen:

• you're getting worse instead of better
• you have trouble breathing or develop other complications, such as a sinus infection
• you have a medical condition (for example, diabetes, heart problems, asthma, or other lung problems)

Most teens can take acetaminophen or ibuprofen to help with fever and aches. Avoid aspirin or any products that contain aspirin, though. If kids and teens take aspirin while they have the flu, it puts them at risk of developing Reye syndrome. Although Reye syndrome is rare, it can be serious.

Antibiotics don't work on viruses, so they won't help someone with the flu get better. Sometimes doctors can prescribe an antiviral medicine to reduce the length of time a person is ill from the flu. These medicines are effective only against some types of flu virus and must be taken within 48 hours after flu symptoms appear. Doctors usually use this medicine for people who are very young, elderly, or ill or at risk for serious complications, like patients with asthma.

Vaccine to the Rescue?

So how do you avoid getting sick during flu outbreaks? Wash your hands often and thoroughly. Avoid sharing cups, utensils, or towels with others. If you do catch the flu, use tissues whenever you sneeze or cough to avoid spreading the virus.

Everyone older than 6 months should get a flu vaccine. Your doctor will probably recommend that you get one.

Flu vaccines are available as a shot or nasal mist. The shot contains killed flu viruses and the nasal mist contains weakened live flu viruses. Both of them will make your body create antibodies that fight off infection if you come into contact with the live flu virus. Because the nasal mist contains live viruses, it is only for healthy people between 2 and 49 years old. Pregnant women should not get the mist. And if you have an egg allergy, get your flu shot in a doctor's office, not at a supermarket, drugstore, or other venue.

Most people don't have reactions to a flu shot, although a few may notice a fever, sore muscles, and tiredness. With the nasal mist vaccine, some people develop a runny nose, headache, and low fever.

The flu vaccine is usually given a few weeks before flu season begins to allow the body time to develop antibodies beforehand. But you can still get a flu vaccine even after flu season starts.

If you do get the flu this season, take care of yourself and call your doctor with any questions or concerns. When you're feeling bad, it can help to remember that the flu usually lasts a week or less and you'll be back to your normal activities before too long.

Reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: September 2012