Cyclobenzaprine for Fibromyalgia Pain

A Muscle Relaxer and Antidepressant

Cyclobenzaprine is a muscle relaxer that is available in generic form as well as under the brand names Flexeril and Amrix. It's considered a second-line treatment for fibromyalgia.

Man in pajamas holding his back in pain
Tom Merton / Getty Images

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

Cyclobenzaprine isn't approved by the U.S. Food and Drug Administration (FDA) for fibromyalgia, but it is frequently prescribed off-label for it.

Cyclobenzaprine relaxes your muscles by acting on your central nervous system. Healthcare providers often prescribe it for muscle injuries as well as for chronic pain.

In studies, this drug has been found to improve sleep quality as well.

Fibromyalgia Studies

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

A 2011 review of drugs used for fibromyalgia found that only one of the three trials included showed that cyclobenzaprine reduced the pain of fibromyalgia. The successful trial also showed improvements in sleep, as well as overall improvement. However, the researchers found no significant differences in stiffness, fatigue, tender points, muscle tightness, or total pain load.

The review found that results from smaller trials were often not significant, possibly because they included too few people.

An earlier analysis of medical literature says that fibromyalgia patients taking cyclobenzaprine were three times as likely to report better sleep, fewer symptoms, and more overall improvement than people in control groups.

In 2011, a small study focused on sleep physiology concluded that very low-dose cyclobenzaprine improved the quality of sleep in people with fibromyalgia. Researchers said they also saw improvements in pain, tenderness, and depression.


A typical adult dosage of cyclobenzaprine is between 5 and 10 milligrams (mg) taken up to three times a day. An extended-release form, which is generally taken in doses of 15 to 30 mg once a day, is also available.

In the fibromyalgia trial on sleep physiology, participants were given steadily escalating doses of 1 to 4 mg taken only at bedtime.

Lower dosages are typically linked to fewer side effects.

Side Effects

Some side effects of cyclobenzaprine are serious enough that you should report them to your healthcare provider immediately. They include:

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

Less serious side effects include:

  • Dry mouth
  • Blurred vision
  • Sleepiness
  • Loss of appetite
  • Stomach pain
  • Diarrhea, constipation, or gas

A Word From Verywell

If you're interested in taking cyclobenzaprine, talk to your healthcare provider about it. They can help you decide whether this medication is potentially beneficial to you as well as safe to take alongside your other medications.

9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Khan I, Kahwaji CI. Cyclobenzaprine. StatPearls. Treasure Island (FL): StatPearls Publishing.

  3. Forte ML, Butler M, Andrade KE, et al. Treatments for fibromyalgia in adult subgroups. Rockville (MD): Agency for Healthcare Research and Quality (US); 2015 Jan. (Comparative Effectiveness Reviews, No. 148.) Appendix A, Medications Used Off Label for Fibromyalgia Syndrome in the United States.

  4. Kia S, Choy E. Update on treatment guideline in fibromyalgia syndrome with focus on pharmacologyBiomedicines. 2017;5(2):20. doi:10.3390/biomedicines5020020

  5. Moldofsky H, Harris HW, Archambault WT, Kwong T, Lederman S. Effects of bedtime very low dose cyclobenzaprine on symptoms and sleep physiology in patients with fibromyalgia syndrome: a double-blind randomized placebo-controlled studyJ Rheumatol. 2011;38(12):2653-2663. doi:10.3899/jrheum.110194

  6. Smith B, Peterson K, Fu R, et al. Drugs for fibromyalgia: final original report. Drug Class Reviews. Oregon Health & Science University, 2011 Apr.

  7. Tofferi JK, Jackson JL, O'Malley PG. Treatment of fibromyalgia with cyclobenzaprine: A meta-analysis. Arthritis and Rheumatism. 2004 Feb 15;51(1):9-13. doi:10.1002/art.20076

  8. Mayo Clinic. Cyclobenzaprine oral route.

  9. Santandrea S, Montrone F, Sarzi-Puttini P, Boccassini L, Caruso I. A double-blind crossover study of two cyclobenzaprine regimens in primary fibromyalgia syndromeJ Int Med Res. 1993;21(2):74-80. doi:10.1177/030006059302100202

Additional Reading

By Adrienne Dellwo
Adrienne Dellwo is an experienced journalist who was diagnosed with fibromyalgia and has written extensively on the topic.