Strains, sprains, and other muscle injuries can result in pain, stiffness, and muscle spasms. Muscle relaxants do not heal the injuries, but they do relaxmuscles and help ease discomfort and stop muscle spasms. The muscle relaxantcyclobenzaprine (Flexeril) is also sometimes used to treat fibromyalgia, a condition that involves aches, stiffness, and fatigue.
Muscle relaxants work by acting on the central nervous system. In the UnitedStates, they are available only with a physician's prescription. Examples ofmuscle relaxants are carisoprodol (Soma), chlorzoxazone (Parafon Forte DSC),cyclobenzaprine (Flexeril), and methocarbamol (Robaxin). Most come only in tablet form. However, methocarbamol (Robaxin) is available in both tablet and injectable forms. Some muscle relaxants are available in Canada without a prescription.
Muscle relaxants are usually prescribed along with rest, exercise, physical therapy, or other treatments. Although the drugs may provide relief, they should never be considered a substitute for these other forms of treatment. Thesedrugs may make the injury feel so much better that one is tempted to go backto normal activity, but doing too much too soon can actually make the injuryworse.
Muscle relaxants work quite well for relieving muscle pain due to injuries, but are not effective for other types of pain. Some people feel drowsy, dizzy,confused, lightheaded, or less alert when using muscle relaxants drugs. These drugs may also cause blurred vision, clumsiness, or unsteadiness.
Because muscle relaxants work on the central nervous system, they may add tothe effects of alcohol and other drugs that slow down the central nervous system. They may also add to the effects of anesthetics, including those used for dental procedures. For this reason, anyone who takes these drugs should notdrive, operate machinery, or do anything else that might be dangerous untilthey have found out how the drugs affect them.
People with certain medical conditions or who are taking certain other medicines can have problems if they take muscle relaxants. Diabetes should be awarethat the metaxalone (Skelaxin) may cause false test results on one type of test for sugar in the urine. People with epilepsy should be cautioned that taking the muscle relaxant methocarbamol may increase the likelihood of seizures.
Anyone who has allergies, who is breastfeeding has kidney disease, has suffered a recent heart attack or irregular heartbeat, has an overactive thyroid gland, hepatitis or liver disease, is a current or former drug or alcohol abuser, has glaucoma, or has problems with urination should discuss their condition with their doctor before taking muscle relaxants.
The most common side effects or muscle relaxants are vision changes, such asdouble vision or blurred vision; dizziness; lightheadedness; drowsiness; anddry mouth. These problems usually go away as the body adjusts to the drug anddo not require medical treatment. Methocarbamol and chlorzoxazone may causeharmless color changes in urine --orange or reddish-purple with chlorzoxazoneand purple, brown, or green with methocarbamol. The urine will return to itsnormal color when the patient stops taking the medicine.
Less common side effects, such as stomach cramps or pain, nausea and vomiting, constipation, diarrhea, hiccups, clumsiness or unsteadiness, confusion, nervousness, restlessness, irritability, flushed or red face, headache, heartburn, weakness, trembling, and sleep problems also may occur and do not need medical attention unless they do not go away or they interfere with normal activities.
More serious side effects are not common, but may occur. Anyone who experiences breathing problems, facial swelling, fainting, unusually fast or unusuallyslow heartbeat, fever, tightness in the chest, rash, itching, hives, burning, stinging, red, or bloodshot eyes, or unusual thoughts or dreams after taking muscle relaxants should seek medical help promptly
The muscle relaxant chlorzoxazone (Parafon Forte DSC) has caused serious, life-threatening liver problems in some people. The reaction is rare, but anyonetaking the drug should stop taking it and notify his or her physician immediately if any of these symptoms occur: fever, rash, loss of appetite, nausea,vomiting, fatigue, pain in the upper right part of the abdomen, dark urine, or yellow skin or eyes.
Muscle relaxants may interact with some other medicines. When this happens, the effects of one or both of the drugs may change or the risk of side effectsmay be greater. Anyone who plans to take muscle relaxants should let the physician know all other medicines, including over-the-counter or nonprescription medicines, that he or she is taking.