Generic Name: cyclobenzaprine (sye kloe BEN za preen)
Brand Name: Amrix, Comfort Pac with Cyclobenzaprine, Fexmid
What is Amrix (cyclobenzaprine)?
Cyclobenzaprine is a muscle relaxant. It works by blocking nerve impulses (or pain sensations) that are sent to your brain.
Cyclobenzaprine is used together with rest and physical therapy to treat skeletal muscle conditions such as pain or injury.
Cyclobenzaprine may also be used for purposes not listed in this medication guide.
What is the most important information I should know about Amrix (cyclobenzaprine)?
You should not use cyclobenzaprine if you have a thyroid disorder, heart block, congestive heart failure, a heart rhythm disorder, or you have recently had a heart attack.
Do not use cyclobenzaprine if you have taken an MAO inhibitor in the past 14 days, such as isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, or tranylcypromine.
What should I discuss with my healthcare provider before taking Amrix (cyclobenzaprine)?
Do not use cyclobenzaprine if you have taken an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, and tranylcypromine.
You should not use cyclobenzaprine if you are allergic to it, or if you have:
a heart rhythm disorder, or you have recently had a heart attack;
congestive heart failure;
heart block; or
a thyroid disorder.
To make sure cyclobenzaprine is safe for you, tell your doctor if you have:
enlarged prostate; or
problems with urination.
Older adults may be more sensitive to the side effects of this medicine.
Cyclobenzaprine is not expected to harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.
It is not known whether cyclobenzaprine passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.
How should I take Amrix (cyclobenzaprine)?
Cyclobenzaprine is usually taken once daily for only 2 or 3 weeks. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Take the medicine at the same time each day.
Do not crush, chew, break, or open an extended-release capsule. Swallow it whole.
You may have unpleasant withdrawal symptoms when you stop taking cyclobenzaprine after long-term use. Ask your doctor how to avoid withdrawal symptoms when you stop using this medicine.
Cyclobenzaprine is only part of a complete program of treatment that may also include rest, physical therapy, or other pain relief measures. Follow your doctor's instructions.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of cyclobenzaprine can be fatal.
What should I avoid while taking Amrix (cyclobenzaprine)?
This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.
Avoid drinking alcohol. Dangerous side effects could occur.
Amrix (cyclobenzaprine) side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Stop using cyclobenzaprine and call your doctor at once if you have:
severe drowsiness, fast heart rate;
tremors or shaking;
pounding heartbeats or fluttering in your chest; or
agitation, hallucinations, fever, overactive reflexes, nausea, vomiting, diarrhea, loss of coordination, fainting.
Common side effects may include:
drowsiness, tired feeling;
blurred vision, dry mouth or throat, altered sense of taste; or
nausea, upset stomach, constipation.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
What other drugs will affect Amrix (cyclobenzaprine)?
Taking cyclobenzaprine with other drugs that make you sleepy or slow your breathing can cause dangerous or life-threatening side effects. Ask your doctor before taking a sleeping pill, narcotic pain medicine, prescription cough medicine, a muscle relaxer, or medicine for anxiety, depression, or seizures.
This list is not complete. Other drugs may interact with cyclobenzaprine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.
More about Amrix (cyclobenzaprine)
Related treatment guides
Where can I get more information?
- Your pharmacist can provide more information about cyclobenzaprine.
- Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
- Disclaimer: Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.
Copyright 1996-2012 Cerner Multum, Inc. Version: 4.03.
Last reviewed: September 19, 2016
Date modified: January 10, 2017