If you have had a cough for more than 3 weeks, it may be chronic. When something is "chronic" it means it lasts for a long time. The following are some questions to help you decide whether you should see your doctor about your cough:

• Are you coughing up phlegm?
• Are you wheezing (making a whistling sound when you breathe in)?
• Are you running a temperature higher than 101°F?
• Are you losing weight without trying?
• Are you having drenching sweats in bed at night (the sheets and your pajamas get soaking wet)?
• Are you coughing up blood?

If you answered "yes" to any of these questions, call your doctor. He or she will want to find out if you have an illness that is causing the cough. If you answered "no" to all of these questions, one of the causes listed below may be causing your cough.

Smoking can cause a cough that doesn't go away. If you smoke, you should stop. Talk to your doctor about using a nicotine replacement product, a prescription medicine or another method to help you stop smoking.

Postnasal drip caused by allergies can make you cough. Postnasal drip is mucus that runs down your throat from the back of your nose. If you have postnasal drip from allergies, try to avoid the things you are allergic to (allergens). Common allergens include the following:

• Dust
• Smoke
• Pollen, mold and freshly cut grass
• Pets
• Certain plants
• Cleaning agents and room deodorizers
• Chemical fumes

An over-the-counter (OTC) medicine may help relieve your allergy symptoms, including a cough. Ask your doctor or pharmacist to help you choose one.

Certain medicines, such as angiotensin-converting enzyme (ACE) inhibitors for high blood pressure, can cause chronic cough. Ask your doctor if any of the medicines you use could cause you to cough. If you are taking a medicine that can cause you to cough, your doctor might be able to prescribe another medicine for you. However, don't stop taking a prescribed medicine unless your doctor tells you to.

Coughing can be a sign of asthma. In some people with mild asthma, a cough may be the only symptom. Your doctor may perform breathing tests to find out if you have asthma. He or she may also ask you to try taking some asthma medicine to see if your cough goes away. If you have asthma, your doctor will help you decide on the right treatment for your symptoms.

Acid from your stomach may back up into your throat. This is called "acid reflux." It can cause heartburn or a cough. Acid reflux is more common when you're lying down. If you have this problem, try raising the head of your bed about 4 inches. It might also help to avoid eating or drinking for a few hours before you lie down. Ask your doctor about OTC or prescription medicines that can help relieve the symptoms of acid reflux by reducing or neutralizing the acid in your stomach.