Flexeril is a commonly prescribed muscle relaxant. It is relatively safe and efficacious in usual doses prescribed. Most often it causes drowsiness and fatigue which is usually self limited and passes with time. Do not drive after taking this drug. Avoid alcohol with this drug. This drug should be used with caution in the elderly since they manifest side effects even at normal doses. Short term use of this drug is usually safe and effective. If you decide to take this drug for a long period of time consult with your health care provider. This drug can have some interactions with other drugs. Check with the pharmacist to run interactions with your other prescription drugs. Do not take more than the maximum prescribed. I am including a link to a scientific paper on the side effects, overdose of this drug. Copy and paste into your browser to view the article. http://www.occup-med.com/content/1/1/16