Cyclobenzaprine is a muscle relaxant available generically and under the brand names Flexeril and Amrix. Considered a second-line drug for fibromyalgia .

This drug is a derivative of the commonly prescribed tricyclic antidepressants for this condition and has similar mild effects.

Cyclobenzaprine is not approved by the US Food and Drug Administration (FDA) for the treatment of fibromyalgia, but it is often used incorrectly.

Cyclobenzaprine relaxes muscles by acting on the central nervous system . Doctors often prescribe it for muscle injuries and chronic pain.

Research has shown that this drug also improves the quality of sleep.

Fibromyalgia Research

Cyclobenzaprine has been studied as a potential treatment for fibromyalgia since the 1980s with mixed results.

A 2011 review of medications used for fibromyalgia found that only one of the three included trials found that cyclobenzaprine reduces fibromyalgia pain. The successful trial also showed improved sleep, as well as an overall improvement. However, the researchers found no significant differences in stiffness, fatigue, pain points , muscle tension, or overall pain load.

The review found that the results of small trials were often marginal, perhaps because so few people were involved.

An earlier review of the medical literature showed that fibromyalgia patients taking cyclobenzaprine were three times more likely to report better sleep, fewer symptoms, and greater overall improvement than controls.

In 2011, a small study on sleep physiology showed that very low doses of cyclobenzaprine improved the quality of sleep in people with fibromyalgia. The researchers said they also noticed a decrease in pain, tenderness and depression .

Dose

The typical dose of cyclobenzaprine for adults is 5 to 10 milligrams (mg) up to three times a day. A sustained-release form is also available, which is usually taken in doses of 15 to 30 mg once a day.

In the Fibromyalgia Sleep Physiology Study, participants received increasing doses of 1 to 4 mg, taken just before bedtime.

Lower doses are generally associated with fewer side effects.

Side effects

Some of the side effects of cyclobenzaprine are serious enough to report to your doctor immediately. They include:

• Allergic reaction (skin rash, hives, swelling of the face, lips or tongue)
• Chest pain or heaviness, especially with pain spreading to the shoulder or arm.
• Fast, rapid, or irregular heartbeat
• Sudden numbness or weakness
• Confusion or loss of coordination
• Sudden headache
• Hallucinations
• Seizures
• Nausea or vomiting

Less serious side effects include:

• Dry mouth
• Blurry vision
• Drowsiness
• Loss of appetite
• Abdominal pain
• Diarrhea, constipation, or gas

Get the word of drug information

If you are interested in taking cyclobenzaprine, talk to your doctor about it. They can help you decide if this medicine is potentially beneficial for you and if it is safe to take with other medicines.