How does this medication work? What will it do for me?

Tizanidine belongs to a group of medications called muscle relaxants. Tizanidine is used to treat spasticity, a condition where muscles in your body spasm, cramp, or become tight due to medical problems such as multiple sclerosis or spine injury. Muscle relaxants work by blocking excess firing of the nerve cells that control muscle movement.

The benefits of tizanidine are related to its effects on the nervous system. The beneficial effects of tizanidine are noticeable within about one hour of taking the first dose.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

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What form(s) does this medication come in?

Zanaflex is no longer being manufactured for sale in Canada. For brands that may still be available, search under tizanidine. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

To reduce the risk of experiencing side effects, the recommended initial adult dose of tizanidine is 2 mg up to 3 times daily. The dose is then increased gradually in 2 mg to 4 mg steps until an effective dose is reached. The most common maintenance dose is 8 mg taken up to 3 times daily (every 6 to 8 hours). Do not take more than 36 mg of tizanidine within a 24-hour period.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without talking to your doctor. Always take tinazidine exactly as prescribed by your doctor.

Tizanidine can be taken with or without meals, however taking tizanidine with food may increase the side effects of this medication. Always take tizanidine the same way, either with food or on an empty stomach.

Stopping the medication suddenly may cause an increase in blood pressure, rapid heart rate and muscle spasms. Talk to your doctor to find a safe way to stop taking the medication.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose of this medicine take it as soon as possible, if you remember within an hour or so of the missed dose. If you do not remember until later, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store tizanidine away from heat and direct light and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

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Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to tizanidine or any ingredients of this medication
  • require muscle spasticity for balance and movement
  • are taking certain medications, such as:
    • ciprofloxacin
    • fluvoxamine
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What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • anxiety
  • back pain
  • constipation
  • depression
  • diarrhea
  • dizziness or lightheadedness, especially when getting up from lying or sitting position
  • drowsiness
  • dry mouth
  • fatigue
  • heartburn
  • increased muscle spasms or tone
  • increased sweating
  • muscle weakness
  • nausea
  • runny nose
  • skin rash
  • sleepiness
  • stomach pain
  • vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

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

  • abdominal pain
  • difficulty speaking
  • flu-like symptoms (e.g., fever, chills, cough, fatigue, sore throat)
  • irregular heartbeat
  • nervousness
  • seeing things that are not there (hallucinations)
  • signs of bleeding in the stomach (e.g., bloody, black, or tarry stools; spitting up of blood; vomiting blood or material that looks like coffee grounds)
  • signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
  • signs of infection (e.g., fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • signs of urinary tract infection (e.g., pain or burning while urinating, increased frequency of urination, or blood in the urine)
  • sores on the skin
  • tingling, burning, or prickling sensations
  • uncontrolled movements of the body
  • unusual tiredness or weakness
  • vision changes

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • seizures

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Birth control: Women taking birth control pills may need a lower dose of tizanidine to achieve a good effect. Birth control pills prevent tizanidine from leaving the body readily and may cause tizanidine to build up in the body leading to side effects.

Drowsiness/reduced alertness: This medication may cause drowsiness and severe dizziness. Do not drive, operate machinery, or perform other potentially hazardous tasks until you have determined how this medication affects you.

Heart rhythm: Tizanidine can cause changes to the normal rhythm of the heart, including an irregular heartbeat called QT prolongation. QT prolongation is a serious life-threatening condition that can cause fainting, seizures, and sudden death. If you are at risk for heart rhythm problems (e.g., people with heart failure, angina, low potassium or magnesium levels), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Tizanidine is removed from the body by the liver and may cause liver problems. If you have liver disease or decreased liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Low blood pressure: Symptoms of severe lowering of blood pressure, such as weakness or dizziness, particularly when rising suddenly from a sitting or lying position, may occur. People who are prone to low blood pressure (e.g., those taking diuretics) should be cautious when using this medication. This effect may happen before the dose of medication is enough to reduce the muscle spasticity. Starting this medication at a very low dose and gradually increasing the daily dose helps to reduce the effect of rapidly dropping blood pressure.

Mental health: Tizanidine can cause hallucinations (e.g., seeing or hearing things that are not really there). People with a history of mental health concerns, such as psychosis or schizophrenia are more likely to experience this effect. If you have a history of mental health issues, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Stopping the medication: Stopping this medication suddenly can cause increased muscle spasms, an increase in blood pressure, or a rapid heart rate. Talk to your doctor before stopping this medication.

Pregnancy: Tizanidine has not been studied for use by pregnant women. In some animal studies, tizanidine caused birth defects and other pregnancy problems. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if tizanidine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using tizanidine has not been established for children less than 18 years of age.

Seniors: Tizanidine is cleared from the body at a slower rate in older adults. This can result in an increase in the number and severity of side effects. The doctor will take this into consideration when determining the dose you should be taking.

What other drugs could interact with this medication?

There may be an interaction between tizanidine and any of the following:

  • acetaminophen
  • alcohol
  • angiotensin converting enzyme (ACE) inhibitors (e.g., captopril, lisinopril, ramipril)
  • beta-blockers (e.g., carvedilol, propranolol, timolol)
  • birth control pills
  • calcium channel blockers (e.g., amlodipine, diltiazem, verapamil, nifedipine)
  • diuretics (water pills; e.g., furosemide, hydrochlorothiazide, spironolactone)
  • fluvoxamine
  • ketoconazole
  • lidocaine
  • mirtazapine
  • phenytoin
  • "quinolone" antibiotics (e.g., ciprofloxacin, norfloxacin, ofloxacin)
  • tricyclic antidepressants (e.g., amitriptyline, desipramine)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.