Generic name: Cyclobenzaprine hydrochloride.

Flexeril is a muscle relaxant. It is thought to work by blocking the reflexes involved in producing and maintaining muscle spasms. 

Quick Facts About Flexeril


Used to relieve muscle spasms. Also provides relief of muscular stiffness and pain.

Flexeril Dosage

Can take with or without food. Is for short-term use (3 weeks or less) only.

  • Usual adult dose: 10 milligrams taken 3 times per day, not to exceed 60 milligrams per day.
  • Usual child dose: not generally prescribed for children under 15 years.
  • Missed dose: take as soon as possible, unless almost within an hour of next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Flexeril Side Effects

Overdose symptoms:

agitation, coma, confusion, congestive heart failure, convulsions, dilated pupils, disturbed concentration, drowsiness, hallucinations, high or low temperature, increased heartbeats, irregular heart rhythms, muscle stiffness, overactive reflexes, severe low blood pressure, stupor, vomiting. High doses may also cause side effects listed below. If you suspect an overdose, immediately seek medical attention.

More common side effects: dizziness, drowsiness, dry mouth.

Less common or rare Flexeril side effects: abnormal heartbeats, abnormal sensations, abnormal thoughts or dreams, agitation, anxiety, bloated feeling, blurred vision, confusion, constipation, convulsions, decreased appetite, depressed mood, diarrhea, difficulty falling or staying asleep, difficulty speaking, disorientation, double vision, excitement, fainting, fatigue, fluid retention, gas, hallucinations, headache, heartburn, hepatitis, hives, increased heart rate, indigestion, inflammation of the stomach, itching, lack of coordination, liver diseases, loss of sense of taste, low blood pressure, muscle twitching, nausea, nervousness, palpitations, rash, ringing in the ears, severe allergic reaction, stomach and intestinal pain, sweating, swelling of the tongue or face, thirst, tingling in hands or feet, tremors, unpleasant taste in the mouth, urinating less than usual, vague feeling of bodily discomfort, vertigo, vomiting, weakness, yellow eyes and skin.


Inform your doctor before combining Flexeril with:

antispasmodic medications such as Donnatal and Bentyl; barbiturates such as phenobarbital; guanethidine (Esimil or Ismelin) and other blood pressure medications; other medications that slow central nervous system such as Halcion and Xanax. Should not take if currently taking MAO inhibitors (Nardil or Parnate) or have taken them within the last 14 days; may cause fatal reaction.

Should not drink alcohol while taking this medication. 

Special Cautions

If pregnant, inform your doctor. Not known if Flexeril appears in breast milk; however, medications related to the ingredients in Flexeril do appear in breast milk.

No special precautions apply to seniors.

Not generally prescribed for children under 15 years.

  • May cause drowsiness and impair your ability to drive a car or operate machinery. Do not take part in any activity that requires alertness.
  • If sensitive to or allergic to this medication, should not take.
  • Use with caution if you have glaucoma or the inability to urinate.
  • If you have: an overactive thyroid, congestive heart failure, irregular heartbeat, or recent heart attack, should not take Flexeril.
  • Flexeril does not relieve other types of pain.
  • This medication is not a substitute for physical therapy, rest, or exercise needed for proper healing of spasms.


HealthSurvey.org provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Flexeril side effects, please contact your healthcare provider.