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Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 313412
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
Tizanidine is indicated for the treatment of spasticity in adults. Tizanidine is a central alpha-2-adrenergic agonist indicated for the treatment of spasticity. (1)
About this medicine
Tizanidine Tablets, USP contains tizanidine hydrochloride as the active ingredient, which is a central alpha 2 -adrenergic agonist. Its chemical name is 5-chloro-4-(2-imidazolin-2-ylamino)-2,1,3-benzothiodiazole monohydrochloride. It has a molecular formula of C 9 H 8 CIN 5 S·HCl and a molecular weight of 290.17. Its structural formula is: Tizanidine hydrochloride is almost white to slightly yellow, crystalline powder, which is odorless or with a faint characteristic odor. Tizanidine hydrochloride is slightly soluble in water and methanol; solubility in water decreases as the pH increases. Tizanidine Tablets, USP are for oral administration and contain active ingredient, tizanidine hydrochloride (2.288 mg equivalent to 2 mg tizanidine base, and 4.576 mg equivalent to 4 mg tizanidine base), and the inactive ingredients, anhydrous lactose, colloidal silicon dioxide, microcrystalline cellulose and stearic acid. Meets USP Dissolution Test 2
Who should not take it
Tizanidine is contraindicated in patients: • taking strong CYP1A2 inhibitors [see Drug Interactions ( 7.1 )]. • with a history of hypersensitivity to tizanidine or the ingredients in tizanidine tablets. Symptoms have included anaphylaxis and angioedema [see Warnings and Precautions ( 5.5 )]. Concomitant use with strong CYP1A2 inhibitors ( 4 , 7.1 ) Patients with a history of hypersensitivity to tizanidine or the ingredients in tizanidine tablets ( 4 , 5.5 )
Warnings and cautions
Hypotension: monitor for signs and symptoms of hypotension, in particular in patients receiving concurrent antihypertensives; tizanidine should not be used with other α 2 -adrenergic agonists ( 5.1 , 7.5 ) Risk of liver injury: monitor ALTs; discontinue tizanidine if liver injury occurs ( 5.2 ) Sedation: Tizanidine may interfere with everyday activities; sedative effects of tizanidine, alcohol, and other central nervous system (CNS) depressants are additive ( 5.3 , 7.4 ) Hallucinations: consider discontinuation of tizanidine ( 5.4 ) 5.1 Hypotension Tizanidine is an α 2 -adrenergic agonist that can produce hypotension [see Adverse Reactions ( 6.1 ) and Drug Interactions ( 7.5 )] . Syncope has been reported in patients treated with tizanidine in the postmarketing setting. The risk of hypotension may be minimized by dose titration; monitoring for signs and symptoms of hypotension prior to dosage increase may minimize the risks associated with hypotension. In addition, patients moving from a supine to fixed upright position may be at increased risk for hypotension and orthostatic effects. Monitor for hypotension when tizanidine is used in patients receiving concurrent antihypertensive therapy. It is not recommended that tizanidine be used with other α 2 -adrenergic agonists. Clinically significant hypotension (decreases in both systolic and diastolic pressure) has been reported with concomitant administration of tizanidine and strong CYP1A2 inhibitors [see Clinical Pharmacology ( 12.3 )] . Therefore, concomitant use of tizanidine with strong CYP1A2 inhibitors is contraindicated [see Contraindications (4) and Drug Interactions ( 7.1 )]. 5.2 Liver Injury Tizanidine may cause hepatocellular liver injury. Liver function test abnormality and hepatotoxicity have been observed with tizanidine [see Adverse Reactions ( 6.1 , 6.2 )]. Monitoring of aminotransferase levels is recommended at baseline and 1 month after maximum dose is achieved, or if hepatic injury is suspected [see Dosage and Administration ( 2.1 ) and Use in Specific Populations ( 8.7 )] . 5.3 Sedation Tizanidine can cause sedation, which may interfere with everyday activity. […]
Reported side effects
The following clinically significant adverse reactions are described elsewhere in other sections of the prescribing information: • Hypotension [see Warnings and Precautions ( 5.1 )] • Liver Injury [see Warnings and Precautions ( 5.2 )] • Sedation [see Warnings and Precautions ( 5.3 )] • Hallucinosis/Psychotic-Like Symptoms [see Warnings and Precautions ( 5.4 )] • Hypersensitivity Reactions [see Warnings and Precautions ( 5.5 )] • Withdrawal Adverse Reactions [ see Warnings and Precautions ( 5.6 )] The most common adverse reactions (greater than 10% of patients taking tizanidine and greater than in patients taking placebo) were dry mouth, somnolence, asthenia, and dizziness. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Apotex Corp. at 1-800-706-5575 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Clinical Trials Experience Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in clinical practice. The safety of tizanidine has been evaluated in three double-blind, randomized, placebo-controlled clinical studies [see Clinical Studies ( 14 )] . Two studies were conducted in patients with multiple sclerosis and one in patients with spinal cord injury. Each study had a 13-week active treatment period which included a 3-week titration phase to the maximum tolerated dose up to 36 mg/day in three divided doses, a 9-week plateau phase where the dose of tizanidine was held constant and a 1-week dose tapering period. In all, 264 patients received tizanidine and 261 patients received placebo. Across the three studies approximately 51% of patients were women, and the median dose during the plateau phase ranged from 20 to 28 mg/day. The most common adverse reactions (>10% of patients treated with tizanidine) reported in multiple dose, placebo-controlled clinical studies involving 264 patients with spasticity were dry mouth, somnolence/sedation, asthenia (weakness, fatigue and/or tiredness), and dizziness. […]
Interactions with other medicines
Moderate or weak CYP1A2 inhibitors: avoid concomitant use; may cause hypotension, bradycardia, or excessive drowsiness; if concomitant use is necessary and adverse reactions occur, reduce tizanidine dosage or discontinue. ( 7.2 , 12.3 ) 7.1 Strong CYP1A2 Inhibitors Concomitant use of tizanidine with strong cytochrome P450 1A2 (CYP1A2) inhibitors (e.g., fluvoxamine, ciprofloxacin) is contraindicated. Changes in pharmacokinetics of tizanidine when administered with a strong CYP1A2 inhibitor resulted in significantly decreased blood pressure, increased drowsiness, and increased psychomotor impairment [see Contraindications ( 4 ) and Clinical Pharmacology ( 12.3 )]. 7.2 Moderate or Weak CYP1A2 Inhibitors Concomitant use of tizanidine with moderate or weak CYP1A2 inhibitors (e.g., zileuton, antiarrhythmics [amiodarone, mexiletine, propafenone, and verapamil], cimetidine, famotidine, oral contraceptives, acyclovir, and ticlopidine) should be avoided. If concomitant use is clinically necessary, and adverse reactions such as hypotension, bradycardia, or excessive drowsiness occur, reduce tizanidine dosage or discontinue tizanidine therapy [see Clinical Pharmacology ( 12.3 )]. 7.3 Oral Contraceptives Concomitant use of tizanidine with oral contraceptives is not recommended. However, if concomitant use is clinically necessary and adverse reactions such as hypotension, bradycardia, or excessive drowsiness occur, reduce or discontinue tizanidine therapy [see Clinical Pharmacology ( 12.3 )]. 7.4 Alcohol and Other CNS Depressants Alcohol increases the exposure of tizanidine after administration of tizanidine. This was associated with an increase in adverse reactions of tizanidine. Concomitant use of tizanidine with CNS depressants (e.g., alcohol, benzodiazepines, opioids, tricyclic antidepressants) may cause additive CNS depressant effects, including sedation. Monitor patients who take tizanidine with another CNS depressant for symptoms of excess sedation [see Clinical Pharmacology ( 12.3 )]. […]
Use in specific groups
Pregnancy: Based on animal data, may cause fetal harm ( 8.1 ) Geriatric use: Tizanidine should be used with caution in elderly patients because clearance is decreased four-fold ( 8.5 ) 8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with use of tizanidine tablets in pregnant women. In animal studies, administration of tizanidine during pregnancy resulted in developmental toxicity (embryofetal and postnatal offspring mortality and growth deficits) at doses less than those used clinically, which were not associated with maternal toxicity (see Animal Data ). In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. The background risk of major birth defects and miscarriage for the indicated population is unknown. Data Animal Data Oral administration of tizanidine (0.3 to 100 mg/kg/day) to pregnant rats during the period of organogenesis resulted in embryofetal and postnatal offspring mortality and reductions in body weight at doses of 30 mg/kg/day and above. Maternal toxicity was observed at the highest dose tested. The no-effect dose for embryofetal developmental toxicity in rats (3 mg/kg/day) is similar to the maximum recommended human dose (MRHD) of 36 mg/day on a body surface area (mg/m 2 ) basis. Oral administration of tizanidine (1 to 100 mg/kg/day) to pregnant rabbits during the period of organogenesis resulted in embryofetal and postnatal offspring mortality at all doses. Maternal toxicity was observed at the highest dose tested. Oral administration of tizanidine (10 and 30 mg/kg/day) during the perinatal period of pregnancy (2 to 6 days prior to delivery) resulted in increased postnatal offspring mortality at both doses. A no-effect dose for embryofetal developmental toxicity in rabbit was not identified. The lowest dose tested (1 mg/kg/day) is less than the MRHD on a mg/m 2 basis. In a pre- and postnatal development study in rats, oral administration of tizanidine (3 to 30 mg/kg/day) resulted in increased postnatal offspring mortality. […]
If too much is taken
review of the safety surveillance database revealed cases of intentional and accidental tizanidine overdose. Some of the cases resulted in fatality and many of the intentional overdoses were with multiple drugs, including CNS depressants. The clinical manifestations of tizanidine overdose were consistent with its known pharmacology. In the majority of cases, a decrease in sensorium was observed including lethargy, somnolence, confusion, and coma. Depressed cardiac function is also observed including most often bradycardia and hypotension. Respiratory depression is another common feature of tizanidine overdose. Should overdose occur, ensure the adequacy of an airway and monitor cardiovascular and respiratory function. Dialysis is not likely to be an efficient method of removing tizanidine from the body [see Description ( 11 )] . In general, symptoms resolve within one to three days following discontinuation of tizanidine and administration of appropriate therapy. Because of the similar mechanism of action, symptoms and management of tizanidine overdose are similar to that following clonidine overdose. For the most recent information concerning the management of overdose, contact a poison control center.
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This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 11 March 2025. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.