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Key takeaways
Robaxin (methocarbamol) and Flexeril (cyclobenzaprine) are skeletal muscle relaxants prescribed for musculoskeletal pain and spasms, with similar central nervous system actions and side effects like drowsiness and dizziness.
Flexeril has been discontinued in brand form but is available in generic formulations and other brand names. It is sometimes prescribed off-label (for a non-FDA-approved use) to treat fibromyalgia.
Both medications have potential side effects including drowsiness, dizziness, and more serious reactions like hypersensitivity, with Flexeril possibly causing more drowsiness.
Robaxin or Flexeril should be used with caution, especially in older adults, due to risks of dizziness, falls, and serious injury. These medications are not recommended for use in pregnant women.
Drug overview & main differences | Conditions treated | Efficacy | Insurance coverage and cost comparison | Side effects | Drug interactions | Warnings | FAQ
Brand-name Flexeril has been discontinued; however, it is still available as a generic—cyclobenzaprine—and as brand names Amrix and Fexmid.
Muscle relaxants are some of the most commonly prescribed medications to treat back pain and other strains or sprains. Robaxin (methocarbamol) and Flexeril (cyclobenzaprine) are examples of skeletal muscle relaxants (SMRs) that your healthcare provider may prescribe if you experience muscle pain.
Both Robaxin and Flexeril work in similar ways through acting on the central nervous system (CNS). Further classified as antispasmodic agents, Robaxin and Flexeril are effective for treating acute, painful musculoskeletal conditions that cause discomfort and muscle spasms. They also have similar side effects such as drowsiness and dizziness.
What are the main differences between Robaxin and Flexeril?
Robaxin
Robaxin, known by its generic name methocarbamol, was released on the market in the 1960s. While its exact mechanism of action is unknown, Robaxin (learn about Robaxin) is believed to relieve discomfort through its sedative effects. It does not directly affect muscle contractions.
Robaxin is available as a brand name or generic medication. It comes as an injection as well as a 500 mg or 750 mg oral tablet. Those who are prescribed Robaxin tablets need to take two or three tablets four times per day, initially. Then, one or two tablets three to four times per day or more is recommended.
Flexeril
Flexeril was initially approved by the FDA in the 1970s. It primarily works on the brain stem and spinal cord in the CNS, which helps reduce motor activity. Flexeril is also structurally similar to tricyclic antidepressants and has similar side effects such as dry mouth and sedation.
Flexeril is commonly known by its generic name cyclobenzaprine. Brand-name Flexeril has been discontinued; however, cyclobenzaprine is available in two other brand names: Amrix (extended-release) and Fexmid (immediate-release). The extended-release tablet can be taken once per day.
RELATED: Learn about Cyclobenzaprine | Learn about Fexmid
| Main differences between Robaxin and Flexeril | ||
|---|---|---|
| Robaxin | Flexeril | |
| Drug class | Muscle relaxant Antispasmodic agent |
Muscle relaxant Antispasmodic agent |
| Brand/generic status | Brand and generic version available | Brand and generic version available Brand name Flexeril has been discontinued in the US. Other brand names include Amrix and Fexmid. |
| What is the generic name? | Methocarbamol | Cyclobenzaprine |
| What form(s) does the drug come in? | Oral tablet Injection |
Oral tablet Oral capsule, extended-release |
| What is the standard dosage? | Initial dosage: 1500 mg 4 times daily Maintenance dosage: 1000 mg 4 times daily, 1500 mg 3 times daily, or 750 mg every 4 hours |
Immediate-release tablets: 5 mg three times daily. Dose may be increased to 10 mg 3 times daily. Extended-release capsules: 15 mg once daily. Dose may be increased to 30 mg once daily. |
| How long is the typical treatment? | Short-term or long-term treatment as directed by your doctor | No more than 2 to 3 weeks |
| Who typically uses the medication? | Adults and young adults ages 16 years or older | Adults and young adults ages 15 years or older |
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Conditions treated by Robaxin and Flexeril
Robaxin and Flexeril are FDA approved to treat discomfort or muscle spasms from acute musculoskeletal conditions as well as tetanus.
Robaxin or Flexeril are usually prescribed to treat musculoskeletal pain such as neck pain. Both drugs are also often used to treat low back pain, a common problem in adults in the US. Up to 80% of adults experience low back pain at some point in their lives.
Flexeril has also been studied to treat fibromyalgia, a chronic condition characterized by muscle pain all over the body. Those with fibromyalgia may experience widespread muscle pain as well as problems with sleep, fatigue, and mood. According to a meta-analysis of five clinical trials, cyclobenzaprine was found to improve sleep and pain in patients with fibromyalgia over a period of up to 24 weeks.
| Condition | Robaxin | Flexeril |
| Muscle spasms | Yes | Yes |
| Musculoskeletal conditions | Yes | Yes |
| Tetanus | Yes | Yes |
| Fibromyalgia | No | Off-label |
Is Robaxin or Flexeril more effective?
Robaxin and Flexeril are effective treatments for treating musculoskeletal pain and muscle spasms. The more effective drug is the one that works best for your specific case.
Flexeril is one of the most studied muscle relaxants; thus, it has more supporting evidence for its effectiveness. In a systematic review, it was found that, in general, muscle relaxants are comparable in effectiveness. This review included other muscle relaxants such as metaxalone, baclofen, tizanidine, orphenadrine, and chlorzoxazone.
In a head-to-head trial between methocarbamol and cyclobenzaprine, there was no significant difference in muscle spasms or tenderness. However, patients experienced slightly better improvements in local pain with cyclobenzaprine (48% vs. 40%). Cyclobenzaprine was also found to produce more somnolence or drowsiness (58% vs. 10%).
Cyclobenzaprine has been compared to Valium (diazepam) and Soma (carisoprodol) in clinical trials. Cyclobenzaprine was similarly effective to these drugs for treating acute low back pain.
Consult a healthcare provider for medical advice to find the best treatment options for you. After a complete assessment from a doctor, one drug may be preferred depending on your overall medical history.
Coverage and cost comparison of Robaxin vs. Flexeril
Generic Robaxin tablets are usually covered by Medicare and insurance plans. Robaxin tablets can be purchased at a retail cost of $31. A SingleCare discount card can lower this price to $8 at participating pharmacies.
Get the SingleCare prescription discount card
Cyclobenzaprine has a higher retail cost of $42.99, compared to Robaxin. Generic cyclobenzaprine tablets are often covered by Medicare and insurance plans. If you don’t have insurance, you can use a SingleCare discount card to cut this cost to less than $8 depending on your pharmacy. Even if you do have insurance, it may be a good idea to find out if you can get a cheaper price on muscle relaxants.
| Robaxin | Flexeril | |
| Typically covered by insurance? | Yes | Yes |
| Typically covered by Medicare? | Yes | Yes |
| Standard dosage | 500 mg tablets (quantity of 30) | 10 mg tablets (quantity of 30) |
| Typical Medicare copay | $0–$47 | $1–$35 |
| SingleCare cost | $7-$17 | $7-$12 |
Common side effects of Robaxin vs. Flexeril
The most common side effects of Robaxin and Flexeril are drowsiness, dizziness, and headache. Flexeril may be associated with more drowsiness compared to Robaxin. Because of its anticholinergic properties, Flexeril can also cause dry mouth.
Both Robaxin and Flexeril can cause some degree of fatigue or nausea.
More serious side effects include hypersensitivity reactions. These allergic reactions can manifest as trouble breathing, severe rash, and swelling. Seek immediate medical attention if you experience these adverse effects.
| Robaxin | Flexeril | |||
| Side effect | Applicable? | Frequency | Applicable? | Frequency |
| Drowsiness | Yes | * not reported | Yes | 29% |
| Dizziness | Yes | * | Yes | 1%–3% |
| Headache | Yes | * | Yes | 5% |
| Dry mouth | No | – | Yes | 21% |
| Fatigue | Yes | * | Yes | 6% |
| Nausea | Yes | * | Yes | 1%–3% |
This may not be a complete list. Consult your doctor or pharmacist for possible side effects.
Source: DailyMed (Robaxin), DailyMed (Flexeril)
Drug interactions of Robaxin vs. Flexeril
Since Robaxin and Flexeril have CNS depressant effects, they can interact with other drugs that have similar effects. Drugs that have CNS depressant effects include barbiturates and benzodiazepines.
Serotonergic drugs including tricyclic antidepressants, selective serotonin reuptake inhibitors (SSRIs), and serotonin norepinephrine reuptake inhibitors (SNRIs), can also cause CNS effects. Taking muscle relaxants with these drugs can cause increased side effects like drowsiness and dizziness.
Robaxin can decrease the effectiveness of pyridostigmine bromide, a medication used to treat myasthenia gravis.
The combination of Flexeril and a monoamine oxidase inhibitor (MAOI) can cause a life-threatening drug interaction. This drug interaction can lead to serotonin syndrome, which can include symptoms like abnormally high fever, tremors, increased sweating, nausea, and vomiting.
| Drug | Drug Class | Robaxin | Flexeril |
| Phenelzine Tranylcypromine Isocarboxazid |
Monoamine oxidase inhibitors (MAOIs) | No | Yes |
| Phenobarbital Pentobarbital Secobarbital |
Barbiturates | Yes | Yes |
| Amitriptyline Nortriptyline Citalopram Fluvoxamine Sertraline |
Serotonergic drugs | Yes | Yes |
| Tramadol Oxycodone Hydrocodone |
Opioids | Yes | Yes |
| Lorazepam Diazepam Alprazolam |
Benzodiazepines | Yes | Yes |
This may not be a complete list of all possible drug interactions. Consult a doctor with all the medications you may be taking.
Warnings of Robaxin and Flexeril
Muscle relaxants should be avoided or monitored before operating machinery or driving a motor vehicle. Muscle relaxants like Robaxin or Flexeril can cause increased dizziness or drowsiness and impair cognitive performance.
Methocarbamol and cyclobenzaprine are not recommended in elderly adults. Both medications are on the BEERS list, a recognized list of medications prepared by the American Geriatrics Society. Muscle relaxants with CNS depressant effects can increase the risk of dizziness, falls, and serious injury in the elderly.
Muscle relaxants are not recommended in pregnant women. These drugs should be kept away from young children.
Muscle relaxants are sometimes abused and can cause physical dependence. Abrupt discontinuation of these drugs after long-term use can cause withdrawal symptoms. These medications should only be used under the supervision of a doctor or healthcare provider.
Frequently asked questions about Robaxin vs. Flexeril
What is Robaxin?
Robaxin is a muscle relaxant that is FDA approved to treat pain and discomfort from musculoskeletal conditions like sprains, back pain, and neck pain. It is available as a generic drug called methocarbamol.
What is Flexeril?
Flexeril is a brand name for cyclobenzaprine, a commonly prescribed muscle relaxant for muscle pain and other musculoskeletal conditions. Cyclobenzaprine is available in immediate-release and extended-release forms.
Are Robaxin and Flexeril the same?
Robaxin and Flexeril are both muscle relaxants. However, they are not the same drug. Robaxin contains methocarbamol and is usually dosed multiple times per day. Flexeril contains cyclobenzaprine and is available in an extended-release form that can be taken once per day.
Is Robaxin or Flexeril better? / Which is better: Flexeril or methocarbamol?
Robaxin and Flexeril are comparable in effectiveness. Some people may prefer extended-release generic Flexeril for its once-daily dosing. But, Flexeril may also cause more adverse effects like drowsiness and dry mouth. Discuss these treatment options with a doctor to find the best medication for you.
Can I use Robaxin or Flexeril while pregnant?
There are no adequate studies to show that Robaxin or Flexeril are safe or harmful during pregnancy. These medications should only be taken if their benefits outweigh the risks. Muscle relaxants should only be taken with medical guidance from a doctor.
Can I use Robaxin or Flexeril with alcohol?
It is not recommended to consume alcohol while on Robaxin or Flexeril. Alcohol can compound muscle-relaxant side effects such as drowsiness, dizziness, or loss of coordination.
Which muscle relaxer is the strongest?
According to systematic reviews, almost all muscle relaxers are comparable in effectiveness. Cyclobenzaprine and tizanidine may be more sedating. However, cyclobenzaprine is one of the most studied muscle relaxers with strong evidence for its effectiveness.
