You don't need a prescription from your doctor to buy an over-the-counter medicine. You take them for minor illnesses, like a headache or a cold.

Your doctor gives you a prescription when over-the-counter medicines don't work or you have a more serious illness.

Over-the-counter medicines are very safe, but you can take too much. For example, if you have a headache, you might take Tylenol to feel better. Tylenol contains an active ingredient for pain relief. The active ingredient is the part of the drug that relieves your symptoms.

Tylenol's active ingredient is acetaminophen. Many other over-the-counter drugs and prescription drugs also contain acetaminophen. If you are taking Tylenol, a cold medication, and a prescription drug with acetaminophen, you could be taking TOO much of that ingredient. This can lead to serious health problems.

Always ask your doctor or pharmacist if it is all right to take over-the-counter medicines and prescription medicines at the same time.

For a chart of common over-the-counter medicines and the active ingredients they contain, go to http://www.bemedwise.org/know_meds/know_meds.htm