Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor as soon as possible. Only your doctor can determine if it is safe for you to continue taking Flexeril. More common side effects may include: Dizziness, drowsiness, dry mouth. Less common or rare side effects may include: Abnormal heartbeats, abnormal sensations, abnormal thoughts or dreams, aggressive behavior, 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, paranoia, 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 more or less than usual, vague feeling of bodily discomfort, vertigo, vomiting, weakness, yellow eyes and skin. Problems such as confusion or hallucinations are more likely in older adults.

The effects of Flexeril during pregnancy have not been adequately studied. If you are pregnant or plan to become pregnant, inform your doctor immediately. It is not known if Flexeril appears in breast milk. However, cyclobenzaprine is related to tricyclic antidepressants, and some of those drugs do appear in breast milk. If this medication is essential to your health, your doctor may advise you to discontinue breastfeeding your baby until your treatment is finished.

Serious, potentially fatal reactions may occur if you take Flexeril with an antidepressant drug known as an MAO inhibitor (such as Nardil, Parnate) or if it has been less than 2 weeks since you last took an MAO inhibitor. You should closely follow your doctor's advice regarding discontinuation of MAO inhibitors before taking Flexeril. Avoid alcoholic beverages while taking Flexeril. If Flexeril is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Flexeril with the following: Barbiturates such as phenobarbital, Guanethidine and other high blood pressure drugs, other drugs that slow the central nervous system, such as Halcion and Xanax Tramadol (Ultram).

Take it as soon as you remember, if it is within an hour or so of your scheduled time. If you do not remember until later, skip the missed dose and go back to your regular schedule. Do not take 2 doses at once.

ADULTS: The usual dose is 10 milligrams 3 times a day. You should not take more than 60 milligrams a day.

Flexeril is not a substitute for the physical therapy, rest, or exercise that your doctor orders for proper healing. Although Flexeril relieves the pain of strains and sprains, it is not useful for other types of pain.

Any medication taken in excess can have serious consequences. If you suspect a Flexeril overdose, seek medical attention immediately. Symptoms of Flexeril overdose may include: 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 also may cause any of the conditions listed in "What Side Effects May Occur?".