What's a Cold?

A cold is an infection of the upper respiratory system. This means it can affect the nose, throat, and sinuses. A cold virus gets inside your body and makes you sick.

Most teens get between two and four colds a year. That's not surprising — colds are the most common infectious disease in the United States, and cause more school absences than any other illness.

What Causes Colds?

Most colds are caused by viruses (called rhinoviruses) that are in invisible droplets in the air you breathe or on things you touch. If one of these viruses gets through the protective lining of the nose and throat, it triggers an immune system reaction. This can cause a sore throat and headache, and make it hard to breathe.

No one knows exactly why people become infected with colds at certain times. But no matter what you hear, sitting or sleeping in a draft, not dressing warmly when it's chilly, or going outside with wet hair will not cause someone to catch a cold.

Dry air — indoors or outside — can lower resistance to infection by viruses. So can allergies, lack of sleep, stress, not eating properly, or being around someone who smokes. And smokers are more likely to catch colds than people who don't smoke. Their symptoms will probably be worse, last longer, and be more likely to lead to bronchitis or even pneumonia.

What Are the Signs and Symptoms of a Cold?

The first symptoms of a cold are often a tickle in the throat, a runny or stuffy nose, and sneezing. You also might feel very tired and have a sore throat, cough, headache, mild fever, muscle aches, and loss of appetite. Mucus from your nose may become thick yellow or green.

Are Colds Contagious?

Yes. Rhinoviruses can stay alive as droplets in the air or on surfaces for as long as 3 hours or even more. So if you touch your mouth or nose after touching someone or something that's been contaminated by one of these viruses, you'll probably catch a cold (unless you're already immune to the particular virus from having been exposed to it before).

If you already have a cold, you're more likely to spread it to others if you don't wash your hands after you cough or sneeze. Going to school or doing normal activities probably won't make you feel any worse. But it will make it more likely that your cold will spread to classmates or friends.

How Long Do Colds Last?

Cold symptoms usually start 2 or 3 days after a person has been exposed to the virus. People with colds are most contagious for the first 3 or 4 days after the symptoms begin and can be contagious for up to 3 weeks. Although some colds can linger for as long as 2 weeks, most clear up within a week.

How Are Colds Treated?

Over-the-counter (OTC) cold medicines can't prevent a cold, but some people think these ease symptoms. They won't help you get better faster, though. And sometimes OTC cold medicines can cause stomach upset or make someone feel dizzy, tired, or unable to sleep. If your nose feels really stuffy, try saline (saltwater) drops to help clear it.

Ask your parents (who can talk with a doctor or pharmacist) what medicine you should take, if any. Most doctors recommend acetaminophen for aches, pains, and fever. If you have a cold, you should not take aspirin or any medicine that contains aspirin, unless your doctor says it's OK. Use of aspirin by teens with colds or other viral illness may increase the risk of developing Reye syndrome, a rare but serious condition that can be fatal. 

Your doctor can let you know if it's OK to take an antihistamine or decongestant, but there is little evidence that these really make a difference.

How Can I Feel Better?

Like all viruses, those that cause colds have to run their course. Getting plenty of rest and drinking lots of fluids can do as much good as medicine as far as helping someone with a cold feel better.

Whether you feel like sleeping around the clock or just taking things a bit easier, pay attention to what your body is telling you when you have a cold. A warm bath or heating pad can soothe aches and pains, and the steam from a hot shower can help you breathe more easily.

Don't worry about whether to feed a cold or starve a fever. Just eat when you're hungry. And you might have heard that chicken soup can cure a cold. There's no real proof of this, but sick people have been swearing by it for more than 800 years.

When Should I Go to the Doctor?

Teens who catch colds usually don't get very sick or need medical attention. But talk to a doctor if any of these things happen to you:

• Your cold symptoms last for more than a week or appear at the same time every year or whenever you're exposed to pollen, dust, animals, or some other substance (you could have an allergy).
• You have trouble breathing or wheeze when you catch a cold (you could have asthma).
• Your symptoms get worse after 3 days or so instead of better (this might mean strep throat, sinusitis, bronchitis, or some other bacterial infection, especially if you smoke).

You should see your doctor if you think you might have more than a cold or if you're getting worse instead of getting better.

Other signs that it's time to call your doctor include:

• coughing that lasts for more than 2–3 weeks
• inability to keep food or liquids down
• increasing headache or facial or throat pain
• severely painful sore throat
• fever of 103°F (39.3°C) or higher, or a fever of 102°F (38.9°C) that lasts for more than a day
• chest or stomach pain
• swollen glands (lymph nodes)
• earache

A doctor won't be able to identify which specific virus is causing a cold. But your doctor can check your throat and ears and possibly also take a throat culture to make sure your symptoms due to another condition. A throat culture is a simple procedure that involves brushing the inside of the throat with a long cotton swab. Examining the germs on the swab will help determine whether you have strep throat and need treatment with antibiotics.

If your doctor does prescribe antibiotics, be sure to take them exactly as directed. If you stop taking them too soon — even if you're feeling better — the infection may not go away and you can develop other problems

Can Colds Be Prevented?

Sooner or later everybody catches a cold. But you can strengthen your immune system's infection-fighting ability by exercising regularly, eating a balanced diet, and getting enough rest.

Although some people recommend alternative treatments for colds (such as zinc and vitamin C in large doses, or herbal products such as echinacea), none of these is proven to prevent or effectively treat colds. Because herbal products can have negative side effects, lots of doctors don't recommend them.