Over-the-Counter Muscle Relaxants for Acute Muscle Spasms
There are no true muscle relaxants available over-the-counter in the United States—all effective skeletal muscle relaxants require a prescription. 1
What Actually Works OTC
The most effective over-the-counter options for acute muscle spasms are topical NSAIDs (like diclofenac gel) with or without menthol, followed by oral NSAIDs (ibuprofen, naproxen) or acetaminophen. 2
First-Line OTC Approach:
- Topical NSAIDs provide the greatest benefit-harm ratio for musculoskeletal injuries including muscle strains and sprains 2
- Oral NSAIDs (ibuprofen 400-800mg or naproxen) are similarly effective when topical options are insufficient 2
- Acetaminophen can reduce pain but is less effective than NSAIDs for musculoskeletal conditions 2
Non-Pharmacologic OTC Measures:
- Ice and elevation reduce swelling and discomfort from acute musculoskeletal injuries 2
- Heat therapy alleviates muscle spasm and low back pain through increased blood flow and reduced muscle tension 2, 3
- Gentle static stretching should be applied during acute muscle cramps until symptoms resolve 4
Prescription Muscle Relaxants (Not OTC)
When OTC options fail, prescription muscle relaxants become necessary:
Most Recommended Prescription Option:
Cyclobenzaprine 5mg three times daily is the preferred prescription muscle relaxant for acute muscle spasm due to its favorable efficacy and side effect profile. 5 The FDA approves cyclobenzaprine as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions, but only for short periods (2-3 weeks maximum). 1
Evidence for Prescription Muscle Relaxants:
- Skeletal muscle relaxants are moderately superior to placebo for short-term pain relief (2-4 days) in acute low back pain, with a relative risk of 0.80 for not achieving pain relief 2
- Cyclobenzaprine 5mg alone is as effective as combination therapy with ibuprofen 400-800mg for acute neck or back pain with muscle spasm 6
- Adding cyclobenzaprine to naproxen reduces objective muscle spasm and tenderness more than naproxen alone 7
Alternative Prescription Options:
- Diazepam 5-10mg three times daily is justified when anxiety, muscle spasm, and pain coexist, though it carries higher risks in older adults 5, 2
- Tizanidine has demonstrated efficacy in 8 trials for acute low back pain 2
Critical Safety Considerations
NSAID Precautions:
Weigh cardiovascular and gastrointestinal risks carefully in patients with hypertension, renal insufficiency, heart failure, or peptic ulcer disease risk, as NSAIDs are associated with serious gastrointestinal events and major coronary events. 2
Prescription Muscle Relaxant Risks:
- Central nervous system adverse events occur twice as frequently (RR 2.04) compared to placebo, including drowsiness, dizziness, and sedation 2, 8
- Muscle relaxants increase fall risk in older adults and should be avoided in this population when possible 2, 5
- Cyclobenzaprine has anticholinergic effects similar to amitriptyline, causing confusion, constipation, urinary retention, and dry mouth 2, 5
Duration Limits:
Use muscle relaxants only for 2-3 weeks maximum, as adequate evidence for longer use is not available and muscle spasm from acute conditions is generally short-duration. 1 Taper gradually over 2-3 weeks if used long-term to prevent withdrawal symptoms including malaise, nausea, and headache. 8
Common Pitfalls to Avoid
- Do not expect OTC "muscle relaxants" marketed as supplements—they lack evidence and FDA approval for muscle spasm 1
- Do not use muscle relaxants believing they directly relieve muscle spasm—their effects are nonspecific and the mechanism remains unclear 2
- Do not overlook aggravating factors like urinary tract infections, constipation, or skin pressure sores that can worsen spasticity 9
- Do not combine muscle relaxants with other CNS depressants without careful monitoring for respiratory depression 5, 10