Cyclobenzaprine – Information, Uses, Side Effects and Dosage


Drug trade name- Amrix, Comfort Pac with Cyclobenzaprine, Fexmid, Flexeril

Category- Muscle Relaxant

Generic name- Cyclobenzaprine

Introduction and Quick Information about Cyclobenzaprine:


Cyclobenzaprine is one of the most effective muscle relaxants, which works by clogging the pain sensations or nerve impulses, which are sent to the brain. Cyclobenzaprine can be taken along with proper physical therapy and rest to treat the skeletal muscle conditions like injury or pain. Also, this medication has been proved to be effective to treat the symptoms of fibromyalgia. Like many other tricyclic antidepressants, Cyclobenzaprine is also prescribed off-label as one of the useful sleeping-aids.

Is Cyclobenzaprine Approved by FDA?

 Yes, the Food and Drug Administration approved Cyclobenzaprine and Amrix (cyclobenzaprine hydrochloride extended-release) in February 2007 to treat such muscle spasm associated with acute, painful musculoskeletal conditions.   

Usage and Benefits of Cyclobenzaprine:

Cyclobenzaprine is one of the effective muscle relaxants, which is available only through prescription. This drug has the potential assistance in relieving the muscle spasms, which are caused due to injuries or any other muscle problems. Muscle spasm is actually an uncontrollable muscle contraction. Muscle spasms can result in stiffness, tenderness, and pain. Sometimes muscle spasms in the neck can cause headaches and back pain.

Most often, muscle spasms are caused by overexertion, injuries or similar problems like sleeping in very twisted positions. Cyclobenzaprine can actually work quite well to treat these sorts of muscle spasms. However, if we talk about muscle spasms occurred due to problems in the spinal cord or brain, such as with spinal cord injury or cerebral palsy. Cyclobenzaprine is not much effective for these kinds of muscle spasms. 

Flexeril (Cyclobenzaprine hydrochloride) is actually a prescription medicine used to relieve tenderness, pain as well as stiffness caused by muscular spasm.

Doctors generally recommend people to take Cyclobenzaprine for just 2-3 weeks. This is usually the sufficient time to allow any muscle damage or injury to heal. In case you feel that the problem persists and has not improved even after 2-3 weeks, then you must consult your health care provider.

Side Effects of Cyclobenzaprine:

Some of the common side effects associated with this medication are:      

  • Uneven, pounding, or fast heartbeats
  • chest pain
  • heavy feeling
  • pain spreading to the shoulder or arm
  • nausea
  • sweating
  • general ill feeling
  • sudden weakness or numbness, particularly on one body side
  • sudden headache
  • confusion
  • problems with speech, vision or balance
  • feeling light-headed or fainting
  • lack of coordination
  • confusion
  • weakness
  • stomach pain
  • loss of appetite
  • low fever
  • unusual behavior or thoughts
  • blurred vision
  • muscle weakness
  • dizziness
  • tired feeling
  • constipation or gas

General Recommended Dosages of Cyclobenzaprine:

You should take Cyclobenzaprine of the prescribed dose by your doctor. Also, never take this drug in extra quantity or for more than recommended.


Take Cyclobenzaprine with one complete glass of water.

Never chew, crush, open or break the extended-release capsules. If you are taking a pill, then swallow it as a whole. Opening or breaking the pill can cause this medication to be released excessively at one point of time.

Cyclobenzaprine is just a part of the complete treatment plan which may also involve physical exercises with the instructions of doctor, carefully follow all the given instructions for better results.

In case I Miss my Dose?

You can simply take the missed dosage immediately as soon as you remember about it. But if it is the time to take the next dose, then simply just skip that missed one. Don’t overdose or take a double dose to compensate for the missed dose.

In case I Take Overdose?

Symptoms of Cyclobenzaprine overdose include fast heartbeat, drowsiness, shaking or tremors, confusion, slurred speech, nausea, vomiting, chest pain, hallucinations, or seizures, symptoms of jaundice, clay- colored stool,etc. Look for emergency medical assistance in case of over dosage.

Drug Interactions of Cyclobenzaprine:

  • bronchodilator like tiotropium (Spiriva) or ipratropium (Atrovent);
  • benztropine (Cogentin), atropine (Donnatal, etc), scopolamine (Transderm-Scop), dimenhydrinate (Dramamine), methscopolamine (Pamine);
  • tramadol (Ultram);
  • glycopyrrolate (Robinul);
  • mepenzolate (Cantil);
  • guanethidine (Ismelin);
  • irritable bowel medicines such as propantheline (Pro-Banthine), hyoscyamine (Levsin, Cystospaz, Anaspaz, etc), dicyclomine (Bentyl),;
  • urinary or bladder medications like flavoxate (Urispas), darifenacin (Enablex), tolterodine (Detrol), oxybutynin (Ditropan, Oxytrol), or solifenacin (Vesicare);

There are many other drugs, which can interact with Cyclobenzaprine. Make sure you inform your health care provider about all the over-the-counter drugs, prescription, minerals, vitamins and herbal products you take.

Lifestyle and Food Habits you must follow when on Cyclobenzaprine:

Lifestyle plays a major role when it comes to the usefulness and efficacy of any treatment. If you are on a healthy track, then of course, you will get out of your problems and conditions very soon. However, if you are leading the unhealthy lifestyle, especially during this treatment, then it might raise some problems. Drinking is one such habits, which not just degrades the physical condition, but acts as a stumbling block in any sort of medical treatment. Hence, it is advisable to stop consuming alcohol if you are taking Cyclobenzaprine simultaneously.

In addition, inform your doctor if you have taken any MAO inhibitor like isocarboxazid (Marplan), tranylcypromine (Parnate), phenelzine (Nardil), or selegiline (Eldepryl, Emsam) within the past 14 days. You must not take Cyclobenzaprine if you have had any heart rhythm disorder, history of heart attack, heart block, congestive heart failure or an overactive thyroid.

How safe is Cyclobenzaprine for Pregnant Women or Nursing Mothers?

Cyclobenzaprine can lead to birth defects or can even harm an unborn infant. Hence, it is advisable to inform your doctor in case you are a nursing mother or are planning to become a mom. Cyclobenzaprine can travel to milk of the mother and further can harm the child.

US FDA pregnancy category B.

B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.


Complications and Conditions Possible due to prolonged use of Cyclobenzaprine:

The prolonged use of Cyclobenzaprine can make the patients addicted. If you try to stop using Cyclobenzaprine abruptly, especially if you have used it for a long time, then it might lead to various withdrawal symptoms. You should always consult your medical practitioner or doctor first before deciding any changes in the treatment plan on your own.

Availability of the Cyclobenzaprine:

Cyclobenzaprine is available only through doctor’s prescription. It is not an over-the-counter drug.