Skelaxin vs. Flexeril: Differences, similarities, and which is better for you

Drug overview & main differences | Conditions treated | Efficacy | Insurance coverage and cost comparison | Side effects | Drug interactions | Warnings | FAQ

Have you ever “thrown out your back” or experienced an injury or sprain where you feel like your muscles are spasming and so tight that you can’t move? If so, your healthcare provider may have prescribed a muscle relaxant to help your symptoms.

Skelaxin and Flexeril are two FDA-approved medications indicated to treat muscle spasms. They are in a group of medications called skeletal muscle relaxants. Skelaxin and Flexeril are most commonly prescribed as their generic counterparts, metaxalone and cyclobenzaprine. The way they work is not completely understood, but may be due to central nervous system (CNS) depression and sedative effects. These medications do not act directly on the muscle or nerves.

Although both medications are muscle relaxants, they are not exactly the same. Continue reading below to learn more about Skelaxin and Flexeril.

What are the main differences between Skelaxin and Flexeril?

Skelaxin is a skeletal muscle relaxant that contains metaxalone. It is available in brand and generic tablets. Skelaxin is used for short-term treatment.

Flexeril is also a skeletal muscle relaxant—the active ingredient is cyclobenzaprine. Flexeril is no longer available commercially as a brand-name product. Flexeril is only available as its generic, cyclobenzaprine. Cyclobenzaprine is also available in an extended-release form with the brand name of Amrix. Flexeril is used for short-term treatment—the manufacturer’s information recommends that Flexeril should not be taken for more than two or three weeks.

Main differences between Skelaxin and Flexeril
	Skelaxin	Flexeril
Drug class	Skeletal muscle relaxant	Skeletal muscle relaxant
Brand/generic status	Brand and generic	Flexeril: available in generic only Amrix: available in brand and generic
What is the generic name?	Metaxalone	Cyclobenzaprine
What form(s) does the drug come in?	Tablet	Tablet, extended-release capsule (brand name Amrix)
What is the standard dosage?	The recommended dose is one (800 mg) tablet or two (400 mg) tablets 3 to 4 times daily	The recommended dose is one tablet (5 mg or 10 mg) 3 times daily Or One tablet (5 mg, 7.5 mg, or 10 mg) at bedtime (less frequent dosing for patients with liver problems or elderly patients)
How long is the typical treatment?	Short-term	Short-term (not recommended for more than 2-3 weeks)
Who typically uses the medication?	Adults and children over age 12 years	Adults and children age 15 years and older

Conditions treated by Skelaxin and Flexeril

Skelaxin and Flexeril are both indicated to be used along with rest, physical therapy, and other measures to relieve the discomfort of acute, painful musculoskeletal conditions like acute low back pain or neck pain.

Both drugs may be prescribed off-label for other conditions, but they are primarily used for muscle spasms. Also, the Flexeril manufacturer information states that the drug is not effective for spasticity associated with cerebral or spinal cord disease, or in children with cerebral palsy.

Condition	Skelaxin	Flexeril
Acute, painful musculoskeletal conditions	Yes	Yes
Fibromyalgia	Off-label	Off-label
Tension headache	Off-label	Off-label
Insomnia	Off-label	Off-label
Acute jaw pain from TMJ	Off-label	Off-label

Is Skelaxin or Flexeril more effective?

American Family Physician states that there is weak (and very little) evidence in terms of muscle relaxants and their efficacy compared to each other. They recommend that the selection of a muscle relaxant should be based on the potential for side effects, drug interactions, abuse, and also patient preference. This publication also reiterates the importance of short-term use of muscle relaxants and that physical therapy and other measures should be taken to prevent long-term use of a muscle relaxant. Other medications such as Tylenol (acetaminophen) or nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, may also be used.

Your healthcare provider can determine if Skelaxin or Flexeril is appropriate for you. He or she will consider your symptoms, medical conditions, medical history, and any medications you take that may interact with Skelaxin or Flexeril.

Coverage and cost comparison of Skelaxin vs. Flexeril

Most insurance plans typically cover Skelaxin in its generic form of metaxalone. Medicare Part D coverage varies. A typical prescription of generic Skelaxin would have an out-of-pocket cost of $147, but you can use a SingleCare coupon to bring the price down to less than $50.

Most insurance and Medicare Part D plans cover Flexeril (generic). Brand-name Flexeril is not available. A typical prescription of generic Flexeril would cost about $20 out-of-pocket, but with SingleCare you can purchase the generic Flexeril for about $7-$8 at participating pharmacies.

	Skelaxin	Flexeril
Typically covered by insurance?	Yes (generic)	Yes (generic)
Typically covered by Medicare Part D?	No	Yes (generic)
Standard dosage	30, 800 mg tablets	30, 10 mg tablets
Typical Medicare copay	$1-$54, depending on the specific plan	$0-$1
SingleCare cost	$48+	$7+

Common side effects of Skelaxin vs. Flexeril

Both drugs can be very sedating. Skelaxin’s most common side effects are drowsiness, dizziness, headache, irritability, nausea, vomiting, and stomach upset.

The most common side effects of Flexeril are drowsiness, dizziness, headache, and dry mouth.

With either drug, an allergic reaction is rare but possible. Serotonin syndrome, a life-threatening condition due to serotonin buildup, is also possible.

	Skelaxin		Flexeril
Side effect	Applicable?	Frequency	Applicable?	Frequency
Drowsiness	Yes	Not reported	Yes	29-38%*
Dizziness	Yes	Not reported	Yes	11%
Headache	Yes	Not reported	Yes	5%
Irritability	Yes	Not reported	Yes	1-3%
Nausea	Yes	Not reported	Yes	1-3%
Vomiting	Yes	Not reported	Yes	1-3%
Stomach upset	Yes	Not reported	Yes	1-3%
Dry mouth	No	–	Yes	21-32%

*Side effect percentages of Flexeril depend on the dose

Source: DailyMed (Skelaxin), DailyMed (Flexeril)

Drug interactions of Skelaxin vs. Flexeril

Skelaxin and Flexeril can potentiate the effects of alcohol, barbiturates, and other CNS depressants, such as benzodiazepines, opioids, antihistamines, and sedative-hypnotics.

There is an increased risk of serotonin syndrome when Skelaxin or Flexeril is taken with other drugs that increase serotonin; such as SSRI, SNRI, or tricyclic antidepressants; triptans for migraine; or cough and cold medications that contain dextromethorphan.

Flexeril is structurally similar to tricyclic antidepressants (such as amitriptyline and nortriptyline). Because of this, there is an increased risk of seizures when taken with tramadol.

Both Skelaxin and Flexeril interact with tramadol (and other opioids)—there is an increased risk of serotonin syndrome as well as additive CNS depression.

This is not a full list of drug interactions. Consult your healthcare provider for medical advice regarding drug interactions.

Drug	Drug class	Skelaxin	Flexeril
Alcohol	Alcohol	Yes	Yes
Pentobarbital Phenobarbital	Barbiturates	Yes	Yes
Alprazolam Clonazepam Diazepam Lorazepam Temazepam	Benzodiazepines	Yes	Yes
Eszopiclone Zaleplon Zolpidem	Sedative hypnotics	Yes	Yes
Codeine Fentanyl Hydrocodone Hydromorphone Methadone Morphine Oxycodone Tramadol	Opioids	Yes	Yes
Phenelzine Selegiline Tranylcypromine	MAO Inhibitors		Yes
Cetirizine Diphenhydramine	Antihistamines	Yes	Yes
Citalopram Escitalopram Fluoxetine Fluvoxamine Paroxetine Sertraline	SSRI antidepressants	Yes	Yes
Desvenlafaxine Duloxetine Venlafaxine	SNRI antidepressants	Yes	Yes
Amitriptyline Desipramine Imipramine Nortriptyline	Tricyclic antidepressants	Yes	Yes
Almotriptan Eletriptan Sumatriptan Zolmitriptan	Triptans	Yes	Yes
Delsym Phenergan-DM Robitussin-DM Tussin-DM	OTC/Rx cough products that contain dextromethorphan	Yes	Yes

Warnings of Skelaxin and Flexeril

Skelaxin

• Use Skelaxin with caution in elderly patients and patients with liver or kidney problems or anemia.
• Taking Skelaxin with food may significantly increase the CNS depression effect. Elderly patients are more susceptible to this effect.

Flexeril

• Do not take an MAO inhibitor within 14 days of Flexeril—the combination could cause seizures and death.
• Patients with hyperthyroidism, heart failure, or other heart or rhythm problems should not take Flexeril. Use Flexeril with caution in elderly patients and patients with liver problems. Do not use the extended-release form (Amrix) in patients with liver problems.
• Use Flexeril with caution in patients with a history of urinary retention, angle-closure glaucoma, increased intraocular pressure, and in patients taking anticholinergic medication.
• Consider withdrawal symptoms when discontinuing Flexeril. Stopping the medicine too quickly may cause headaches, fatigue, and nausea.
• Swallow Amrix (extended-release cyclobenzaprine) capsules whole. Do not chew or crush.

Skelaxin and Flexeril warnings in common

• Both medications are on the list of Beers criteria, meaning that they are potentially inappropriate for older adults (age 65 and older). Most older adults do not tolerate muscle relaxants well due to serious side effects, sedation, and increased risk of fractures. Also, the effectiveness is questionable at the doses that may be tolerated in this age group.
• Overdose deaths (deliberate or accidental) have occurred from Skelaxin or Flexeril, especially in combination with antidepressants or alcohol. Monitor patients closely.
• Serotonin syndrome may occur. Patients and their caregivers should be aware of the symptoms (sweating, fever, agitation, change in blood pressure or heart rate, tremor, nausea, vomiting, diarrhea) and seek immediate medical attention if symptoms occur. Serotonin syndrome is more likely to occur if you take Skelaxin or Flexeril in combination with other drugs that increase serotonin, such as certain antidepressants, triptans, or cough and cold preparations that contain dextromethorphan.
• Do not drive or operate machinery until you know how you react to Skelaxin or Flexeril. Both drugs cause drowsiness and dizziness.

Frequently asked questions about Skelaxin vs. Flexeril

What is Skelaxin?

Skelaxin is a skeletal muscle relaxant used for the acute treatment of muscle spasms. The generic name for Skelaxin is metaxalone.

What is Flexeril?

Flexeril is also a muscle relaxant used to treat skeletal muscle spasms. The generic name of Flexeril is cyclobenzaprine.

Are Skelaxin and Flexeril the same?

Although Skelaxin and Flexeril are both in the same drug category (skeletal muscle relaxants), they do have some differences, such as side effects, dose, and pricing, as outlined above.

Is Skelaxin or Flexeril better?

No data directly compares the two drugs in terms of pain relief. Therefore, if you need a muscle relaxant, your healthcare provider will consider your symptoms, conditions, and any medications you take (that could interact with Skelaxin or Flexeril) to determine if one of these drugs is better for you.

Can I use Skelaxin or Flexeril while pregnant?

The Skelaxin manufacturer information states, “Post-marketing experience has not revealed evidence of fetal injury, but such experience cannot exclude the possibility of infrequent or subtle damage to the human fetus. Safe use of metaxalone has not been established with regard to possible adverse effects upon fetal development.” Therefore, Skelaxin is not recommended for use in pregnant women (especially in early pregnancy) or women who may become pregnant, unless your healthcare provider determines that benefits outweigh risks.

The Flexeril manufacturer information states that there are no adequate, well-controlled studies in pregnant women. Therefore, Flexeril should be used in pregnant women only if clearly needed.

Can I use Skelaxin or Flexeril with alcohol?

No. Using Skelaxin or Flexeril with alcohol can increase the side effects such as dizziness and drowsiness. It can also lead to impaired coordination, which can cause accidents. Also, taking a muscle relaxant with alcohol can increase the chance of abuse or dependence.

Is Skelaxin a strong muscle relaxer?

Any muscle relaxant, including the following list, should be effective in treating acute muscle pain/spasms when used at the proper dose. Consult your healthcare provider for more information.

• Skelaxin (metaxalone)
• Flexeril (cyclobenzaprine)
• Zanaflex (tizanidine)
• Robaxin (methocarbamol)
• Soma (carisoprodol)
• Lorzone (chlorzoxazone)
• Lioresal (baclofen)
• Dantrium (dantrolene)
• Norflex (orphenadrine)
• Valium (diazepam)
• Miltown (meprobamate)

Does Skelaxin help with pain?

Yes, Skelaxin helps with the pain of acute muscle spasms. The manufacturer recommends using Skelaxin along with rest, physical therapy, and other measures. The way it works is not entirely understood but is likely due to central nervous system depression. Skelaxin does not directly work on the muscles or nerves.

Is Skelaxin safe?

Like any medication, Skelaxin has benefits as well as side effects and risks. See the Warnings section above for more information. If your healthcare provider has determined that Skelaxin is appropriate for you and is compatible with any medical conditions you have and medications you take, you will likely be able to safely take Skelaxin (for short-term use) with no significant issues. Consult your healthcare provider for medical advice.