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.