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Tizanidine (Systemic)

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Tizanidine (Systemic)

US Brand Names

• Zanaflex


Tizanidine (tye-ZAN-i-dine) is used to help relax certain muscles in your body. It relieves the spasms, cramping, and tightness of muscles caused by medical problems such as multiple sclerosis or certain injuries to the spine. Tizanidine does not cure these problems, but it may allow other treatment, such as physical therapy, to be more helpful in improving your condition.

Tizanidine acts on the central nervous system (CNS) to produce its muscle relaxant effects. Its actions on the CNS may also cause some of the medicine's side effects.

This medicine is available only with your doctor's prescription, in the following dosage form:


    • Tablets (U.S.)

Special Considerations

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For tizanidine, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to tizanidine. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.


Tizanidine has not been studied in pregnant women. However, studies in animals have shown that tizanidine causes birth defects and other pregnancy problems. Before taking this medicine, make sure your doctor knows if you are pregnant or if you become pregnant.


Tizanidine may pass into the breast milk. However, this medicine has not been reported to cause problems in nursing babies.


Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of tizanidine in children with use in other age groups.

Older adults

Studies in older adults show that tizanidine stays in the body a little longer than it does in younger adults. Your doctor will consider this when deciding on your dose.

Other medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking tizanidine, it is especially important that your health care professional know if you are taking any of the following:

    • Antihypertensives (high blood pressure medicine)-Severe low blood pressure may occur

    • Oral contraceptives (birth control pills)-The chance of side effects may be increased

    • Phenytoin-Tizanidine may increase the blood levels of phenytoin, which increases the chance of serious side effects

Other medical problems

The presence of other medical problems may affect the use of tizanidine. Make sure you tell your doctor if you have any other medical problems, especially:

    • Kidney disease or

    • Liver disease-The chance of side effects may be increased; higher blood levels of tizanidine may result and a smaller dose may be needed


Take this medicine only as directed. Do not take more of it and do not take it more often than recommended on the label, unless otherwise directed by your doctor. To do so may increase the chance of side effects.


The dose of tizanidine will be different for different patients. Follow your doctor's orders or the directions on the label . The following information includes only the average doses of tizanidine. If your dose is different, do not change it unless your doctor tells you to do so.

    • For oral dosage form (tablets):

      o For muscle relaxation:

        Adults-The dose is 8 milligrams (mg) every six to eight hours as needed. No more than 36 mg should be taken within a twenty-four-hour period.

        Children-Use and dose must be determined by your doctor.

Missed dose

If you miss a dose of this medicine, and you remember within an hour or so of the missed dose, take it as soon as you remember. However, if you do not remember until later, skip the missed dose and go back to your regular dosing schedule. Do not double doses.


To store this medicine:

    • Keep out of the reach of children.

    • Store away from heat and direct light.

    • Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.

    • Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.


Your doctor should check your progress at regular visits, especially during the first few weeks of treatment with this medicine. During this time the amount of medicine you are taking may have to be changed often to meet your individual needs.

Do not suddenly stop taking this medicine . Unwanted effects may occur if the medicine is stopped suddenly. Check with your doctor for the best way to reduce gradually the amount you are taking before stopping completely.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; other muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using tizanidine .

This medicine may cause dizziness, drowsiness, lightheadedness, clumsiness or unsteadiness, or vision problems in some people. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert, well-coordinated, and able to see well .

Tizanidine may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if dry mouth continues for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.

Dizziness, lightheadedness, or fainting may occur when you get up suddenly from a lying or sitting position. Getting up slowly may help lessen this problem.

Side Effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

More common

Fever; loss of appetite; nausea and/or vomiting; nervousness; pain or burning while urinating; sores on the skin; tingling, burning, or prickling sensations; yellow eyes or skin.

Less common

Black, tarry stools; bloody vomit; blurred vision; chills or sore throat; coldness; convulsions (seizures); cough; dry, puffy skin; eye pain; fainting; irregular heartbeat; kidney stones; seeing things that are not there; unusual tiredness or weakness; weight gain.

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common

Anxiety; back pain; constipation; depression; diarrhea; difficulty in speaking; dizziness or lightheadedness, especially when getting up from a lying or sitting position; drowsiness; dry mouth; heartburn; increased sweating; increased muscle spasms or tone; muscle weakness; pain or burning in throat; runny nose; skin rash; sleepiness; stomach pain; uncontrolled movements of the body.

Less common

Difficulty swallowing; dry skin; joint or muscle pain or stiffness; loss of hair; migraine headache; mood changes; neck pain; swelling of feet or lower legs; swollen area that feels warm and tender; trembling or shaking; unusual feeling of well-being; weight loss.

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

April 15, 1999

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