The skeletal muscle relaxants are a diverse set of drugs that are used for treating muscle spasticity or spasms, which can cause pain and interfere with your functional ability. Spasticity, or having stiff, rigid muscles with exaggerated reflexes, generally lasts a long time. It arises from conditions affecting the brain and/or spinal cord, such as cerebral palsy, multiple sclerosis, and stroke. Muscle spasms, on the other hand, are usually temporary and are associated with conditions affecting the muscles, bones, and associated structures, such as tension headaches, back or neck pain, and fibromyalgia.

While these are widely prescribed drugs, the evidence supporting the effectiveness of the nine available muscle relaxants is sparse, and some studies are of questionable quality. Many of the avai lable studies are old and do not meet current standards. While the available evidence indicates that the drugs can help relieve symptoms, the poor quality of the research makes it difficult to draw firm conclusions about whether any one drug is superior to the others. Also, most of these medicines cause sedation as a side effect, and some of them pose a risk of serious problems, such as liver toxicity and addiction.

Muscle spasticity

Taking into consideration all of the evidence on muscle relaxants for spasticity, our Best Buy pick is:

  • Generic baclofen tablet

Baclofen costs between $27 and $60 for a 30-day supply, so you could save a significant amount of money over some of the more expensive brand-name muscle relaxants, which can cost $200 to up to $486 a month. If you are unable to tolerate baclofen, we recommend trying generic tizanidine.

Muscle spasms

If you have a musculoskeletal problem-such as headache, back or neck pain- fibromyalgia or other conditions that cause spasms that have not responded to nondrug therapies, then pain relievers such as acetaminophen (Tylenol and generics) or non-steroidal anti-inflammatory drugs, or NSAIDS (aspirin, ibuprofen, naproxen) are a reasonable first option. The muscle relaxants have not been found to be any better than these painkillers for providing relief. Plus, the muscle relaxants can cause sedation and other serious side effects. If you can't tolerate acetaminophen or NSAIDs because of kidney or liver problems, bleeding ulcers or heart issues, then you may want to consider trying a muscle relaxant.

If you and your doctor have decided to try a muscle relaxant to treat muscle spasms, taking all of the evidence into consideration, we chose the following as a Best Buy:

  • Generic cyclobenzaprine tablet

Cyclobenzaprine is supported by the strongest body of evidence. Also, it is available in a generic form that costs $8 to $15 for a seven-day course, which makes it one of the least expensive muscle relaxants and significantly less expensive than brand-name ones that can run more than $100. If cyclobenzaprine is not effective or causes you side effects that you can't tolerate, you could try methocarbamol or chlorzoxazone, both of which are available as inexpensive generics. We recommend avoiding carisoprodol (Soma) because it is associated with a high risk of abuse and addiction potential not seen with other skeletal muscle relaxants.

In addition to sedation, the most common side effects associated with muscle relaxants include weakness or fatigue, dizziness, and dry mouth.

This report was released in December 2009.