Cyclobenzaprine Side Effects

June 4th, 2013 by Helen Scholz

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.

Do not take cyclobenzaprine if you have used an MAO inhibitor such as isocarboxazid (Marplan), tranylcypromine (Parnate), phenelzine (Nardil), or selegiline (Eldepryl, Emsam) within the past 14 days. Serious, life-threatening side effects can occur if you take cyclobenzaprine before the MAO inhibitor has cleared from your body.

You should not take cyclobenzaprine if you have recently had a heart attack, or if you have a heart rhythm disorder, congestive heart failure, heart block, or an overactive thyroid.

Cyclobenzaprine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert. Avoid drinking alcohol, which can increase some of the side effects of cyclobenzaprine.

Get emergency medical help if you have any of these signs of an allergic reaction: 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 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. You may report side effects to FDA at 1-800-FDA-1088.