Cyclobenzaprine vs methocarbamol: muscle relaxants compared
Cyclobenzaprine (Flexeril) and methocarbamol (Robaxin) are the two most prescribed muscle relaxants for short-term back and neck spasms. Cyclobenzaprine is more sedating and has more interactions; methocarbamol is taken more often each day and is often chosen for older adults.
Updated October 4, 2026
At a glance
- How often
- Cyclobenzaprine
- Up to three times a day, or once a day extended-release
- Methocarbamol
- Three or four times a day
- Drowsiness
- Cyclobenzaprine
- Common and often marked
- Methocarbamol
- Common, usually milder
- Interactions
- Cyclobenzaprine
- Many: MAOIs, serotonin-affecting medicines, sedatives
- Methocarbamol
- Fewer: mainly alcohol and other sedatives
- Use in older adults
- Cyclobenzaprine
- Generally avoided
- Methocarbamol
- Used with caution
- Generic
- Cyclobenzaprine
- Yes
- Methocarbamol
- Yes
Cyclobenzaprine Flexeril, Amrix | Methocarbamol Robaxin | |
|---|---|---|
| How often | Up to three times a day, or once a day extended-release | Three or four times a day |
| Drowsiness | Common and often marked | Common, usually milder |
| Interactions | Many: MAOIs, serotonin-affecting medicines, sedatives | Fewer: mainly alcohol and other sedatives |
| Use in older adults | Generally avoided | Used with caution |
| Generic | Yes | Yes |
What they are for
Both are approved for short-term relief of painful muscle spasm, alongside rest, heat, gentle activity and pain relievers such as anti-inflammatories. They are meant for a few weeks at most; long-term use is not recommended, and evidence for benefit beyond the first couple of weeks is limited.
Why cyclobenzaprine needs more care
Cyclobenzaprine is chemically related to tricyclic antidepressants. It causes dry mouth and drowsiness, must not be taken with an MAOI, can cause serotonin syndrome with tramadol or serotonin-affecting antidepressants, and is generally avoided in people with heart rhythm problems, an overactive thyroid, or older age, when confusion and falls are more likely.
Methocarbamol in practice
Methocarbamol has fewer drug interactions, though alcohol, opioids and other sedatives still add to drowsiness. It can turn urine brown, black or green, which is harmless. Because it is taken more often, a schedule or reminders help.
Cost
Both are inexpensive generics. The extended-release cyclobenzaprine capsule costs more than the standard tablets, so ask for a quote on the form prescribed.
Missed doses and warning signs
If you miss a dose, take it when you remember unless the next is near, and never double up. Neither needs tapering after a short course. If the spasm lasts more than a few weeks, or comes with numbness, leg weakness, or trouble controlling your bladder or bowels, see a clinician promptly, as these can signal a problem that needs more than a muscle relaxant.
Questions for your prescriber
- Which is safer with my other medicines and my age?
- How long should I take it, and what else should I do for the spasm?
- Is it safe for me to drive while taking it?
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Sources
Written by the Script Unlock editorial team from the sources above. It is general information, not advice for you or your pet; your prescriber decides which medicine is right.
Script Unlock is a marketplace that lets licensed pharmacies quote a cash price on your prescription. It does not prescribe, dispense or sell medication, does not process patient payments, and does not give medical advice. Always follow the instructions of your prescriber and pharmacist and read the medication guide supplied with your medicine.