Muscle Relaxer - Flexeril

cylobenzaprine - Flexeril
cylobenzaprine - Flexeril. LAGUNA DESIGN/Collection:Science Photo Library/Getty Images

Muscle Relaxer - Flexeril

Muscle spasm treatment can range from massage and stretching on the holistic side to drugs on the conventional medical side.  

Related:  How to Relieve Back Muscle Spasms

To help release very tight muscle spasms, some people take Flexeril. Approved by the FDA in 1977, this drug is but one type of skeletal muscle relaxer.

Below is a fact sheet about Flexeril, including side effects, generic information, dosage and storage information, and more.

Related:  Types of Skeletal Muscle Relaxers

Flexeril Names

Flexeril is the brand name for cyclobenzaprine.  Cyclobenzaprine is the active ingredient and the generic form of the drug.  Either way, this medication is available by prescription only.

Action of Flexeril

Flexeril is sometimes used short-term, in conjunction with physical therapy and rest for acute cases of muscle injury, for example, sprains and strains.  By relaxing ultra-tight muscles, it may help you make faster progress with your home exercise program.

As a skeletal muscle relaxer, cyclobenzaprine works in the central nervous system, indirectly influencing motor neurons of the brainstem and spinal cord to relieve spasms.

How and When Flexeril is Taken (and Not Taken)

As with any medication take Flexeril or cyclobenzaprine according to your doctor's or pharmacist's instructions.  It's meant to be used for about 2-3 weeks, i.e. not for the long term.

Generally, Flexeril or cyclobenzaprine is taken three times per day in tablet form.  Immediate release tablets contain 5 or 10 mg, while extended release tablets contain 15 or 30 mg.  Don't take it upon yourself to increase your dosage.  If you feel you need more, speak with your doctor.

If you miss a dose, and it is now closer the time of the next dose, just resume taking the medication with the next scheduled time.

Do not double dose to make up for a missed dosage.

Storing Flexeril

Store cyclobenzaprine/Flexeril at room temperature or as instructed by the pharmacist.

Side Effects, Complications, and Precautions Related to Taking Flexeril:

While a number of potential side effects and complications for taking Flexeril exist, one of the most important is the potential for drowsiness or dizziness.  Don't drive or operate machinery or do anything that requires you to be alert while you're under the influence of this drug.  And avoid alcohol, as well.

Some of the most common side effects include but are not limited to:

  • dry mouth
  • drowsiness
  • dizziness
  • tiredness
  • constipation
  • blurred vision
  • unpleasant taste
  • nervousness
  • confusion
  • abdominal pain or discomfort

Serious side effects are rare, but if these do occur they require prompt medical attention.  These include, but are not limited to:

  • mental and mood changes, for example, hallucinations and confusion
  • difficulty in urinating
  • dark urine
  • fast, pounding and/or irregular heartbeat
  • fainting
  • yellowing of the eyes and/or skin
  • stomach and/or abdominal pain
  • persistent nausea, vomiting and/or lack of appetite
  • seizures
  • loss of coordination

Note that the elderly will be more sensitive to side effects associated with this medication, and pregnant women should use Flexeril/cyclobenzaprine only if directed by their doctor.  The drug may also pass on to breast milk.

According to, cyclobenzaprine may contain inactive ingredients which sometimes cause allergic reactions.  Be sure to talk with your doctor and pharmacist about this before taking.  You also should be transparent about any liver disease, thyroid problems, heart problems, glaucoma and/or difficulty urinating you've had in the past.  This way, she can determine if you are at risk for a complication.

The same is true for other medications you may be taking.

Related:  Choose an Effective Pain Medication


Flexeril.  RxList website.  Accessed: Feb 2016.

Cyclobenzaprine, Flexeril, Amrix. website. Accesed: Feb 2016.

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