Muscle Relaxants

What Are Muscle Relaxants?

Muscle relaxants are a group of medications used to reduce muscle spasm and tension. Despite their name, they don't directly relax muscles but work on the brain and nervous system to reduce muscle-related pain. They're typically used short-term for acute muscle problems but sometimes prescribed for chronic conditions.¹

How They Work²

Most work on the central nervous system
Reduce signals that cause muscle spasm
Sedating effect may contribute to relief
Don't directly act on muscle tissue

Common Muscle Relaxants

Cyclobenzaprine (Flexeril)

Most commonly prescribed
Structurally similar to tricyclic antidepressants
Very sedating

Methocarbamol (Robaxin)

Less sedating option
Available over-the-counter in some countries

Tizanidine (Zanaflex)

Works differently (alpha-2 agonist)
Often used for spasticity
Can lower blood pressure

Baclofen (Lioresal)

GABA agonist
Used for spasticity from MS, spinal injury
Must taper off slowly

Carisoprodol (Soma)

High abuse potential
Controlled substance
Generally avoided

Common Uses

Acute back pain with spasm
Neck pain and strain
Fibromyalgia (some)
Spasticity conditions
Tension headaches

Side Effects³

Drowsiness (most common)
Dizziness
Dry mouth
Blurred vision
Constipation
Difficulty urinating

Precautions

Don't drive until you know effects
Avoid alcohol (dangerous sedation)
Use caution with other sedating medications
Elderly more sensitive to effects
May be habit-forming
Usually prescribed short-term

For Chronic Pain

Limited evidence for long-term use
May be helpful at bedtime
Should be part of broader plan
Discuss risks and benefits with doctor

References

See S, Ginzburg R. Choosing a skeletal muscle relaxant. Am Fam Physician. 2008;78(3):365-370.
Chou R, Peterson K, Helfand M. Comparative efficacy and safety of skeletal muscle relaxants for spasticity and musculoskeletal conditions. J Pain Symptom Manage. 2004;28(2):140-175.
Toth PP, Urtis J. Commonly used muscle relaxant therapies for acute low back pain: a review of carisoprodol, cyclobenzaprine hydrochloride, and metaxalone. Clin Ther. 2004;26(9):1355-1367.