Uses

What is cyclobenzaprine used for?

Cyclobenzaprine is commonly used to treat muscle spasms from an injury or problem that causes muscle or joint pain.

Cyclobenzaprine may also be used for other conditions as determined by your healthcare provider.

How does cyclobenzaprine work (mechanism of action)?

Cyclobenzaprine works by calming down muscle cramps in specific areas of the body without affecting the overall muscle function. It helps reduce excessive muscle activity, which lessens muscle tension and helps relieve pain and stiffness associated with muscle cramps.

How is cyclobenzaprine supplied (dosage forms)?

Brands and other names

  • Amrix
  • Fexmid

Dosage forms and strengths

  • 5 mg, 7.5 mg, 10 mg oral tablets
  • 15 mg, 30 mg extended-release oral capsules

How should I store cyclobenzaprine?

Cyclobenzaprine should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place, in a tightly closed container. Protect from light.

Side Effects

What are the most common side effects of cyclobenzaprine?

The most common side effects of cyclobenzaprine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Dry mouth
  • Dizziness
  • Tiredness or drowsiness
  • Headache
  • Nausea, indigestion, and constipation (extended-release capsule)

There may be other side effects of cyclobenzaprine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of cyclobenzaprine?

While less common, the most serious side effects of cyclobenzaprine are described below, along with what to do if they happen.

Serotonin Syndrome. Serotonin syndrome is when there is too much of a substance called serotonin in your body. Cyclobenzaprine can cause serotonin syndrome when it is taken alone or with other medicines that affect serotonin. This condition can be life-threatening. Get emergency help if you have any of the following symptoms of serotonin syndrome.

  • Sweating, fever, or flushing
  • Confusion
  • Feeling agitated or restless
  • Seeing or hearing unusual things
  • Dizziness
  • Fast or racing heartbeat
  • Nausea, vomiting, or diarrhea
  • Muscle twitching, stiffness, or tremor
  • Seizures

Heart Effects. Cyclobenzaprine may increase your risk of certain effects on the heart, such as raising your heart rate or causing an abnormal heart rhythm (arrhythmia). Stop taking cyclobenzaprine right away and call your healthcare provider or get medical attention right away if you have chest pain, a fast or irregular heartbeat, or if you feel your heartbeat more than usual.

Warnings & Precautions

Who should not use cyclobenzaprine?

Allergies to Ingredients. People who are allergic to any of the following should not take cyclobenzaprine.

  • Cyclobenzaprine
  • Amrix
  • Fexmid
  • Flexeril
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific cyclobenzaprine products they stock.

Drug Interactions. Cyclobenzaprine should not be taken while you are using certain other medicines. Before taking cyclobenzaprine, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section below for more details.

Heart Problems. Cyclobenzaprine should not be taken if you have any of the following heart problems.

  • You just had a heart attack
  • Your heart is not pumping as well as it should be (heart failure)
  • You have an abnormal heart rhythm (arrhythmia), including heart block or other conduction problems

Overactive Thyroid (Hyperthyroidism). Cyclobenzaprine should not be taken if you have overactive thyroid.

What should I know about cyclobenzaprine before using it?

Do not take cyclobenzaprine unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share cyclobenzaprine with other people, even if they have the same condition as you. It may harm them.

Keep cyclobenzaprine out of the reach of children.

Cyclobenzaprine extended-release capsules should be swallowed whole. If you have trouble swallowing cyclobenzaprine extended-release capsules, you can open the capsule and pour the powder from inside the capsule onto a small amount of applesauce (like a tablespoonful). You should swallow the applesauce right away, without chewing it.

You should take cyclobenzaprine extended-release capsules around the same time each day. 

Cyclobenzaprine may affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how cyclobenzaprine affects you.

If you have been taking cyclobenzaprine for a long time, you should not suddenly stop taking it without talking to your healthcare provider. Stopping cyclobenzaprine suddenly, after taking it for a long time, may cause nausea, headache, and a general feeling of being unwell, tired, or not having your usual energy. 

People who are 65 or older may be at a greater risk for some side effects of cyclobenzaprine. Talk to your healthcare provider about your risks if you are in this age group.

Cyclobenzaprine is usually only taken for short periods of time (usually less than two or three weeks). Check with your healthcare provider to see how long you should take cyclobenzaprine.

What should I tell my healthcare provider before using cyclobenzaprine?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if cyclobenzaprine is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following.

  • Eye problems, such as glaucoma or increased eye pressure
  • Trouble emptying your bladder
  • Brain or spinal cord problems 
  • Cerebral palsy

Liver Problems. Cyclobenzaprine should not be used if your liver is not working as well as it should be. If there is a concern about the health of your liver, your healthcare provider may do tests to determine if it is working well enough to take this medicine.

Pregnancy. It is not known if or how cyclobenzaprine could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take cyclobenzaprine while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if cyclobenzaprine passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take cyclobenzaprine while breastfeeding.

Interactions

Does cyclobenzaprine interact with foods or drinks?

There are no known interactions between clonazepam and foods or nonalcoholic drinks.

Do not drink alcohol while taking cyclobenzaprine. It is unknown if drinking alcohol will affect cyclobenzaprine. The risk of dizziness, drowsiness, or tiredness may be increased if you drink alcohol while taking cyclobenzaprine.

Does cyclobenzaprine interact with other medicines (drug interactions)?

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking cyclobenzaprine.

  • A monoamine oxidase inhibitor (MAOI) within the past 2 weeks, which is a medicine usually used for depression or Parkinson’s disease
  • A barbiturate, such as phenobarbital, butalbital, or primidone, which is a medicine that may be used to treat insomnia, migraines, or seizures
  • A selective serotonin reuptake inhibitor (SSRI) or serotonin and norepinephrine reuptake inhibitor (SNRI), which is a medicine commonly used for anxiety and depression
  • Any other medicine that causes dizziness and sleepiness, such as prescription pain medicines, sleep medicines, and medicines for anxiety
  • An anticholinergic medicine, which includes antihistamines and medicines commonly used for overactive bladder, Parkinson’s disease, or stomach problems
  • Tramadol, which is a medicine commonly used for pain
  • A tricyclic antidepressant, such as amitriptyline, nortriptyline, or protriptyline, even if it is not used for depression
  • An antipsychotic, which is a medicine for certain mental health conditions
  • Verapamil (Verelan, Verelan PM), which is a medicine used for high blood pressure or chest pain
  • Bupropion (Wellbutrin, others), which is a medicine used for depression or to help someone stop smoking
  • Meperidine (Demerol), which is an opioid medicine used to treat pain

This may not be a complete list of medicines that can interact with cyclobenzaprine. Always check with your healthcare provider.

Does Cyclobenzaprine interact with other drugs you are taking?
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Overdose/Missed Dose

What should I do if I accidentally use too much cyclobenzaprine?

If you or someone else has taken too much cyclobenzaprine, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of cyclobenzaprine?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses. 

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