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Amrix

Last reviewed on RxList: 6/17/2019
Amrix Patient Information Including Side Effects

Brand Names: Amrix, Comfort Pac with Cyclobenzaprine, Fexmid, Flexeril

Generic Name: cyclobenzaprine

What is 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 relieve muscle spasms caused by painful conditions such as an injury.

Cyclobenzaprine may also be used for purposes not listed in this medication guide.

What are the possible side effects of cyclobenzaprine?

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:

  • fast or irregular heartbeats;
  • chest pain or pressure, pain spreading to your jaw or shoulder; or
  • sudden numbness or weakness (especially on one side of the body), slurred speech, balance problems.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Serious side effects may be more likely in older adults.

Common side effects may include:

  • drowsiness, tiredness;
  • headache, dizziness;
  • dry mouth; or
  • upset stomach, nausea, 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.

What is the most important information I should know about 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.

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Amrix Patient Information including How Should I Take

What should I discuss with my healthcare provider before taking cyclobenzaprine?

You should not use cyclobenzaprine if you are allergic to it, or if you have:

  • a thyroid disorder;
  • heart block, heart rhythm disorder, congestive heart failure; or
  • if you have recently had a heart attack.

Cyclobenzaprine is not approved for use by anyone younger than 15 years old.

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.

Some medicines can interact with cyclobenzaprine and cause a serious condition called serotonin syndrome. Be sure your doctor knows if you also take stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. Ask your doctor before making any changes in how or when you take your medications.

Tell your doctor if you have ever had:

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

It may not be safe to breast-feed while using this medicine. Ask your doctor about any risk.

Older adults may be more sensitive to the effects of this medicine.

How should I take cyclobenzaprine?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Cyclobenzaprine is usually taken once daily for only 2 or 3 weeks. Follow your doctor's dosing instructions very carefully.

Swallow the capsule whole and do not crush, chew, break, or open it.

Take the medicine at the same time each day.

Call your doctor if your symptoms do not improve after 3 weeks, or if they get worse.

Store at room temperature away from moisture, heat, and light.

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Amrix Patient Information including If I Miss a Dose

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

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.

Overdose symptoms may include severe drowsiness, vomiting, fast heartbeats, tremors, agitation, or hallucinations.

What should I avoid while taking cyclobenzaprine?

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Avoid drinking alcohol. Dangerous side effects could occur.

What other drugs will affect cyclobenzaprine?

Using cyclobenzaprine with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

This list is not complete. Other drugs may affect cyclobenzaprine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

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.
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.

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