Zolpidem is a sedative, also called a hypnotic. It affects chemicals in your brain that may become unbalanced and cause sleep problems (insomnia).

Zolpidem is used to treat insomnia. The immediate-release form of zolpidem is Ambien, which is used to help you fall asleep. The extended-release form of zolpidem is Ambien CR, which has a first layer that dissolves quickly to help you fall asleep, and a second layer that dissolves slowly to help you stay asleep.

Your doctor will determine which form of this medicine is best for you.

Zolpidem may also be used for other purposes not listed in this medication guide.

Most important: Zolpidem may cause a severe allergic reaction. Stop taking zolpidem and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Zolpidem will make you fall asleep. Never take this medicine during your normal waking hours, unless you have a full 7 to 8 hours to dedicate to sleeping.

Some people using this medicine have engaged in activity such as driving, eating, or making phone calls and later having no memory of the activity. If this happens to you, stop taking zolpidem and talk with your doctor about another treatment for your sleep disorder.

Zolpidem can cause side effects that may impair your thinking or reactions. You may still feel sleepy the morning after taking the medication. Until you know how zolpidem will affect you during waking hours, be careful if you drive, operate machinery, pilot an airplane, or do anything that requires you to be awake and alert.

Do not drink alcohol while you are taking zolpidem. It can increase some of the side effects of zolpidem, including drowsiness.

Zolpidem may be habit-forming and should be used only by the person it was prescribed for. This medicine should never be shared with another person, especially someone who has a history of drug abuse or addiction. Keep the medication in a secure place where others cannot get to it.

It is dangerous to try and purchase zolpidem on the Internet or from vendors outside of the United States. Medications distributed from Internet sales may contain dangerous ingredients, or may not be distributed by a licensed pharmacy. Samples of zolpidem purchased on the Internet have been found to contain haloperidol (Haldol), a potent antipsychotic drug with dangerous side effects. For more information, contact the U.S. Food and Drug Administration (FDA) or visit www.fda.gov/buyonlineguide