Flexeril Side Effects

Generic name: cyclobenzaprine

Note: This document contains side effect information about cyclobenzaprine. Some of the dosage forms listed on this page may not apply to the brand name Flexeril.

Some side effects of Flexeril may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

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

Get emergency medical help if you have any of these signs of an allergic reaction while taking cyclobenzaprine (the active ingredient contained in Flexeril) hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using cyclobenzaprine and call your doctor at once if you have any of these serious side effects:

• fast, pounding, or uneven heartbeats;

• chest pain or heavy feeling, pain spreading to the arm or shoulder, nausea, sweating, general ill feeling;

• sudden numbness or weakness, especially on one side of the body;

• sudden headache, confusion, problems with vision, speech, or balance;

• feeling light-headed, fainting;

• confusion, weakness, lack of coordination;

• nausea, stomach pain, low fever, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

• seizure (convulsions);

• unusual thoughts or behavior, hallucinations (seeing things); or

• easy bruising or bleeding, unusual weakness.

Less serious side effects of cyclobenzaprine may include:

• dry mouth or throat;

• blurred vision;

• drowsiness, dizziness, tired feeling;

• loss of appetite, stomach pain, nausea;

• diarrhea, constipation, gas; or

• muscle weakness.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect.

For Healthcare Professionals

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

Nervous system

Elderly patients may be particularly susceptible to the sedation and confusion which may accompany cyclobenzaprine (the active ingredient contained in Flexeril) therapy.

Nervous system side effects are common and include drowsiness in up to 40% of treated patients and dizziness in up to 11%. Fatigue, asthenia, headache, nervousness, blurred vision, and confusion have also been reported.

Other

Other side effects have included anticholinergic effects such as dry mouth (in as many as 27% of treated patients), and, less frequently, dry skin, blurry vision, constipation, and an organic brain syndrome. Paradoxical sweating has also been reported.

Psychiatric

Psychiatric side effects including mania and psychosis have been reported rarely. A case of hallucinations has also been reported.

Hypersensitivity

Hypersensitivity side effects have included rash, angioedema, and pruritus. Anaphylaxis has been reported rarely.

Cardiovascular

Cardiovascular side effects have included cardiac arrhythmias, tachycardia, and hypotension.

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