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Fexmid Side Effects

Generic name: cyclobenzaprine

Medically reviewed by Drugs.com. Last updated on Feb 14, 2025.

Note: This document provides detailed information about Fexmid Side Effects associated with cyclobenzaprine. Some dosage forms listed on this page may not apply specifically to the brand name Fexmid.

Applies to cyclobenzaprine: oral capsule extended release, oral suspension, oral tablet.

Precautions

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it.

If your condition does not improve within 2 or 3 weeks, or if it becomes worse, check with your doctor.

Do not use the extended-release capsules if you have used an MAO inhibitor (MAOI) such as Eldepryl®, Marplan®, Nardil®, or Parnate® within 14 days of each other.

Check with your doctor right away if you have anxiety, restlessness, a fast heartbeat, fever, sweating, muscle spasms, twitching, nausea, vomiting, diarrhea, or see or hear things that are not there. These may be symptoms of a serious condition called serotonin syndrome. Your risk may be higher if you also take certain other medicines that affect serotonin levels in your body.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds, sedatives, tranquilizers, or sleeping medicine, prescription pain medicine or narcotics, medicine for seizures or barbiturates, other muscle relaxants, or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.

This medicine may cause some people to have blurred vision or to become drowsy, dizzy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert and able to see well.

Cyclobenzaprine may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Common side effects of Fexmid

Some side effects of cyclobenzaprine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common side effects

  • blurred vision
  • dizziness, drowsiness, or lightheadedness
  • dryness of the mouth

Less common or rare side effects

  • bloated feeling or gas, indigestion, nausea or vomiting, or stomach cramps or pain
  • constipation
  • diarrhea
  • excitement or nervousness
  • frequent urination
  • general feeling of discomfort or illness
  • headache
  • muscle twitching
  • numbness, tingling, pain, or weakness in hands or feet
  • pounding heartbeat
  • problems in speaking
  • trembling
  • trouble sleeping
  • unpleasant taste or other taste changes
  • unusual muscle weakness
  • unusual tiredness

Serious side effects of Fexmid

Along with its needed effects, cyclobenzaprine (the active ingredient contained in Fexmid) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking cyclobenzaprine:

Rare side effects

  • clumsiness or unsteadiness
  • confusion
  • fainting
  • mental depression
  • problems in urinating
  • ringing or buzzing in the ears
  • skin rash, hives, or itching occurring without other symptoms of an allergic reaction listed above
  • unusual thoughts or dreams
  • yellow eyes or skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking cyclobenzaprine:

Symptoms of overdose

For healthcare professionals

Applies to cyclobenzaprine: compounding powder, oral capsule extended release, oral tablet, oral and topical kit.

General adverse events

The most frequently occurring adverse reactions have included dry mouth, dizziness, fatigue, constipation, nausea, dyspepsia, and somnolence.[Ref]

Nervous system

Elderly patients may be particularly susceptible to the sedation and confusion which may accompany cyclobenzaprine therapy.[Ref]

Psychiatric

Hypersensitivity

Gastrointestinal

Hepatic

Cardiovascular

Other

Dermatologic

Genitourinary

Musculoskeletal

Ocular

Respiratory

See also:

References

1. (2016) "Product Information. Amrix (cyclobenzaprine)." A-S Medication Solutions

2. (2001) "Product Information. Flexeril (cyclobenzaprine)." Merck & Co., Inc

Frequently asked questions

Further information

Fexmid side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.