The most effective medicines for muscle spasms depend on whether you’re dealing with a temporary cramp from overuse or an ongoing condition involving nerve damage. For everyday muscle spasms, over-the-counter pain relievers like ibuprofen or naproxen are the typical first step. For more severe or persistent spasms, prescription muscle relaxants such as cyclobenzaprine or methocarbamol are the most commonly used options.
Over-the-Counter Pain Relievers
NSAIDs (nonsteroidal anti-inflammatory drugs) like ibuprofen and naproxen are often the first choice for muscle spasms because they reduce both pain and inflammation at the site of the spasm. They won’t directly stop a muscle from contracting involuntarily, but they address the pain and swelling that often accompany spasms, which can break the cycle of pain triggering more tightness.
Acetaminophen (Tylenol) can help with pain but doesn’t reduce inflammation, making it less useful when swelling is part of the problem. Topical versions of NSAIDs, applied as gels or creams directly over the affected muscle, deliver relief locally with fewer gastrointestinal side effects than pills. However, clinical trials have shown mixed results for topical formulations, with some studies finding no meaningful advantage over placebo for pain relief in the first few days.
Prescription Muscle Relaxants
When over-the-counter options aren’t enough, prescription muscle relaxants fall into two distinct categories that work very differently.
Antispasmodics are prescribed for the kind of muscle spasms most people experience: acute pain from a back injury, a stiff neck, or musculoskeletal strain. These drugs work through the central nervous system, dialing down the signals that cause muscles to clench. The most commonly prescribed antispasmodics include:
- Cyclobenzaprine is the most widely studied. Patients taking it are significantly more likely to report improvement within two weeks compared to placebo, with roughly one in three people experiencing meaningful relief specifically because of the drug. It’s typically taken two to three times daily for short periods.
- Methocarbamol is another common option, often used for acute injuries. It tends to cause somewhat less sedation than cyclobenzaprine for some people, though drowsiness is still common.
- Carisoprodol works similarly but carries a higher risk of dependency and has been linked to greater injury risk, particularly from falls.
Antispastics are a separate class reserved for spasticity, a condition where nerve damage in the brain or spinal cord causes muscles to tighten uncontrollably. This happens in conditions like multiple sclerosis, spinal cord injuries, or after a stroke. Baclofen is the most commonly used antispastic. It works by reducing the release of chemical signals that excite nerve cells in the spinal cord, essentially calming overactive nerve pathways. Dantrolene takes a different approach entirely, acting directly on muscle fibers to reduce their ability to contract forcefully. These drugs are not interchangeable with antispasmodics and are not appropriate for a pulled muscle or typical back pain.
How Well Do Muscle Relaxants Actually Work?
The evidence is more modest than many people expect. For acute low back pain, which is the most common reason muscle relaxants are prescribed, a systematic review found they moderately improved pain and function for the first several days of treatment. But adding cyclobenzaprine to naproxen didn’t improve outcomes compared to naproxen alone after one week. For chronic pain, muscle relaxants perform no better than placebo.
Head-to-head comparisons between different muscle relaxants show no clear winner. Studies comparing cyclobenzaprine and carisoprodol found no statistically significant differences in overall pain scores. The choice between them often comes down to side effect profiles and individual response rather than one being dramatically more effective than another.
Side Effects to Expect
Drowsiness is the dominant side effect across nearly all muscle relaxants. Most of these drugs work on the central nervous system, so sedation, dizziness, and foggy thinking come with the territory. This is why they’re generally recommended for short-term use, often just a week or two, and why taking them before bed can be a practical strategy.
For older adults, these side effects are especially concerning. A study of over 300,000 older adults found that those using muscle relaxants had a 32% higher risk of injury compared to non-users. Carisoprodol carried the highest risk at 73% increased odds of injury, followed by methocarbamol at 42% and cyclobenzaprine at 22%. The sedation and confusion these drugs cause can lead to falls, which is why most geriatric guidelines recommend avoiding muscle relaxants in elderly patients altogether.
Liver safety varies by drug. Chlorzoxazone and dantrolene have been linked to serious liver injury, including rare cases of liver failure. Tizanidine also carries liver risk. By contrast, cyclobenzaprine, methocarbamol, and carisoprodol have very little evidence of causing significant liver problems.
What About Magnesium Supplements?
Magnesium is one of the most popular natural remedies for muscle cramps, but the clinical evidence is disappointing. A Cochrane review analyzing multiple studies found that magnesium supplementation, at doses ranging from 100 to 520 mg of elemental magnesium daily, did not significantly reduce cramp frequency, intensity, or duration compared to placebo after one month of use. The review concluded that magnesium is unlikely to be effective for unexplained muscle cramps at any tested dose.
That said, if you have a confirmed magnesium deficiency (which blood tests can identify), correcting it may help. The research suggesting magnesium doesn’t work specifically looked at people with cramps that had no clear underlying cause. Gastrointestinal side effects like diarrhea are common with oral magnesium, affecting 11% to 37% of people in the studies reviewed.
Matching the Treatment to the Spasm
For an occasional charley horse or muscle cramp after exercise, you likely don’t need prescription medication at all. Stretching the affected muscle, applying heat or ice, staying hydrated, and taking an NSAID if the pain lingers is usually sufficient.
For acute injuries like a pulled back muscle that causes days of painful spasms, a short course of a prescription muscle relaxant alongside an NSAID is a standard approach. The key word is short. These medications work best in the first several days and lose their advantage quickly. They’re meant to get you through the worst of it while the underlying injury heals, not to be taken long-term.
For spasticity caused by neurological conditions, treatment looks completely different. Drugs like baclofen or dantrolene are used on an ongoing basis, often alongside physical therapy, and are carefully titrated to balance spasm control against side effects like muscle weakness. Tizanidine is another option for spasticity, though it requires monitoring for liver function given its association with liver injury.