Flexeril vs. Zanaflex
See how Flexeril and Zanaflex compare on approved uses, dosing, side effects, and cost.
Key Takeaways
Flexeril treats short-term muscle spasm from injuries and isn't meant for use beyond 2 to 3 weeks, while Zanaflex is approved for ongoing spasticity from conditions like multiple sclerosis or spinal cord injury.
Both drugs commonly cause drowsiness and dry mouth, but Zanaflex also requires periodic liver testing and carries risks of low blood pressure and slowed heart rate.
Flexeril typically costs less each month than Zanaflex, though both are available as generics.
Flexeril vs. Zanaflex Drug Summary
Flexeril
Flexeril (cyclobenzaprine) is a tricyclic-related skeletal muscle relaxant used short-term for spasms from acute muscle injuries. It's taken as an oral tablet, usually three times a day, along with rest and physical therapy. Only the generic form is sold in the U.S. today.
Zanaflex
Zanaflex (tizanidine) is a central alpha-2 agonist muscle relaxant used to manage spasticity in adults with conditions like MS. It's taken as an oral tablet or capsule, increased gradually across several doses each day. Its effects wear off quickly, so doses are often timed to specific activities.
Flexeril vs. Zanaflex Side Effects
Flexeril
Zanaflex
Flexeril vs. Zanaflex Dosage
Flexeril
Zanaflex
| STAGE | DOSE | WHEN |
| Starting dose | 5 mg three times daily | At the start |
| Maximum dose | 10 mg three times daily | If needed |
| Dose changes | 1 increase | As tolerated |
| STAGE | DOSE | WHEN |
| Starting dose | 2 mg every 6-8 hours | At the start |
| Maximum dose | 36 mg/day maximum | If needed |
| Dose changes | 4 increases | As tolerated |
Flexeril
| STAGE | DOSE | WHEN |
| Starting dose | 5 mg three times daily | At the start |
| Maximum dose | 10 mg three times daily | If needed |
| Dose changes | 1 increase | As tolerated |
Zanaflex
| STAGE | DOSE | WHEN |
| Starting dose | 2 mg every 6-8 hours | At the start |
| Maximum dose | 36 mg/day maximum | If needed |
| Dose changes | 4 increases | As tolerated |
Flexeril vs. Zanaflex Indications
Flexeril
Flexeril is FDA-approved as a short-term add-on to rest and physical therapy for muscle spasm from acute musculoskeletal injuries, like a back strain. It is not approved for spasticity caused by conditions such as cerebral palsy or spinal cord injury. Some clinicians use it off-label for fibromyalgia pain and sleep symptoms.
Adjunct to rest and physical therapy for acute spasm
Short-term use only, typically 2 to 3 weeks
Off-label: fibromyalgia pain and sleep symptoms
Not effective for spasticity from CNS disease
Zanaflex
Zanaflex is FDA-approved to manage spasticity in adults, a condition often caused by multiple sclerosis, spinal cord injury, or stroke. It works directly on the central nervous system to reduce muscle tightness rather than treating short-term spasm. It is not approved for use in children.
Management of spasticity from MS or spinal injury
Used for ongoing, chronic muscle tightness
Dosing often timed around specific daily activities
Not approved for pediatric patients
Flexeril vs. Zanaflex Pros and Cons
Flexeril
Flexeril works well for short-term, acute muscle spasm and has decades of clinical use behind it. It is not intended for long-term treatment and carries several cardiac-related contraindications. Coverage is usually straightforward because inexpensive generics have long been available.
Pros
Lower typical monthly cost than Zanaflex
No liver enzyme monitoring required
Long track record of clinical use since 1977
Three tablet strengths for flexible dosing
Cons
Not recommended for use beyond 2 to 3 weeks
Ineffective for spasticity from CNS conditions like MS
Contraindicated with several heart conditions and MAOIs
Drowsiness affects up to 39% of patients
Zanaflex
Zanaflex is approved for longer-term spasticity management and offers dosing flexibility timed to specific activities. Its side effect profile includes hypotension, sedation, and a need for liver monitoring at higher doses. Cost is typically higher than short-term muscle relaxants like Flexeril.
Pros
Approved for long-term spasticity, not just short-term spasm
Effective for spasticity from MS or spinal cord injury
Short duration lets dosing match specific activities
Available generically, reducing cost versus brand
Cons
Higher typical monthly cost than Flexeril
Requires liver enzyme monitoring at baseline and peak dose
Can cause hypotension, bradycardia, and syncope
Risk of rebound hypertension if stopped abruptly
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