Tizanidine dosage, forms, and strengths

Tizanidine (brand name: Zanaflex) is a generic prescription muscle relaxant FDA approved to manage muscle spasticity due to multiple sclerosis, brain injury, spinal cord injury, amyotrophic lateral sclerosis (ALS), and stroke. Healthcare providers may use it off-label to treat back pain, neck pain, muscle cramps, chronic migraine headaches, or (in combination with an NSAID) medication overuse headaches. As a muscle relaxant, tizanidine slows down the nerves in the spinal cord called motor neurons that cause muscles to contract. This reduces spasms and muscle rigidity. Tizanidine is taken as a tablet or capsule as needed, but there are limits on how often and how many doses can be taken during the day. Doses start small. If needed, the prescriber will increase the dose every few days until an effective individualized dose is reached. 

Tizanidine forms and strengths

Tizanidine is taken by mouth as a capsule or tablet. These formats are not equivalent, so they can’t be substituted without a dose adjustment.

• Capsule: 2 milligrams (mg), 4 mg, 6 mg

• Tablet: 2 mg, 4 mg

Tizanidine dosage for adults

Tizanidine dosages for spasticity are individualized. The doses start on the lower endand if needed, the healthcare provider will slowly increase the dose until an effective dose is reached. The upper limit (maximum dosage) is 36 mg daily, divided into several doses.

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Tizanidine dosage for spasticity

Healthcare professionals prescribe tizanidine to relax spastic or rigid muscles due to neurological conditions such as multiple sclerosis, amyotrophic lateral sclerosis, traumatic brain injury, spinal cord injuries, or stroke. Dosages are individualized. Healthcare providers will start with a low dose: one 2 mg tablet taken as needed. Up to three doses can be taken daily, provided each dose is separated from the previous by at least six to eight hours. If needed, the prescriber will gradually increase the dose (called titration) by 2–4 mg every few days until an effective dose is reached. 

• Standard adult dosage for spasticity: Doses are individualized between 2 mg doses as needed for up to three doses per day (6 mg per day) to a total of up to 36 mg per day

• Maximum adult dosage for spasticity: a total of 36 mg per day, divided into doses

Tizanidine dosage for children

The use of tizanidine has not been FDA-approved as safe and effective in children or adolescents. When healthcare providers use tizanidine off-label to treat spasticity in pediatric patients, the dosage will be based on age and body weight.

• Starting dosage for spasticity in children 2–9 years old: 1 mg (half of a 2 mg tablet) taken once per day at bedtime

• Starting dosage for spasticity in children 10–17 years old: 2 mg tablet taken once per day at bedtime

• Standard dosage for spasticity in children 2–17 years old: 0.3–0.5 mg/kg per day divided into three or four doses

• Maximum dosage for spasticity in children 2–17 years old: 24 mg per day (divided into three or four doses)

Tizanidine dosage restrictions

Tizanidine is eliminated by the liver and the kidneys. People with liver disease or kidney problems can have problems with increased levels of tizanidine in the blood, depending on the extent of their condition. This increases the risk of tizanidine side effects such as blurred vision, dry mouth, constipation, and serious side effects such as slowed heartbeat or low blood pressure. 

Because doses are individualized, there are no specific dosing guidelines for people with renal or hepatic impairment. Instead, the healthcare provider may start at a lower dose, and (if needed) will increase the dose more slowly than in other people until an effective dose is reached. 

Tizanidine dosage for pets 

Skeletal muscle relaxants are commonly prescribed to cats and dogs to relieve muscle pain, tremors, muscle spasms, and muscle rigidity. The most commonly used muscle relaxants in dogs and cats are methocarbamol, guaifenesin injections, diazepam, and baclofen. Dosages are based on the dog’s weight. Some veterinarians may prescribe tizanidine for problems such as a slipped or herniated disk, but this is uncommon. Dosages have not been standardized.

How to take tizanidine

In adults, tizanidine is taken as an oral tablet or capsule on an as-needed basis up to three times per day. Doses are taken at least six to eight hours apart. In adults, no more than three doses are taken in a single day.

• Take tizanidine as directed. The dose may need to be changed by the healthcare provider several times to find the most effective dose.

• Take a tizanidine dose when needed unless directed otherwise by the prescriber. The effects only last briefly, so it’s best to take it before activities that require relief from muscle spasms.

• Do not take doses larger than prescribed.

• Individual doses should be separated by at least six to eight hours.

• Do not take more than three doses per day.

• Do not switch between tablets and capsules without getting a new prescription.

• Tizanidine tablets may be scored to divide individual tablets into two or four doses. Ask the prescriber or pharmacist how to divide tablets.

• Take this medicine with or without food, but always take it the same way. Tizanidine works differently depending on whether you take it on an empty or full stomach. Talk to the prescriber if there are any questions about this.

• Store the medicine in a closed container with a child-resistant closure at room temperature, away from direct light, heat, and moisture. Keep out of reach and out of sight of children and pets.

Tizanidine dosage FAQs

How long does it take tizanidine to work?

In most cases, the effects of tizanidine should be apparent about one hour after taking the drug. The effects of tizanidine tablets will reach their peak effectiveness at controlling muscle spasms and rigidity in about one hour. The effects typically fade after three to six hours. Taken without food, tizanidine capsules work about the same as tizanidine tablets. 

Taking the tablet with food can increase the level of tizanidine in your body, but it may take longer to work. On the other hand, taking the capsule with food can decrease the level of tizanidine in your body. 

How long does tizanidine stay in your system?

Tizanidine is a short-acting drug. Its effects peak in one to two hours after taking the drug. With a half-life (the time it takes for about half the drug to be cleared from the body) of 2.5 hours, a tizanidine dose falls to undetectable levels in the bloodstream in about 12 hours.

What happens if I miss a dose of tizanidine?

Tizanidine is a short-acting medicine taken as needed. Prescribers typically advise people to take tizanidine before daily activities requiring some relief of muscle spasticity or rigidity. Doses can be taken six to eight hours apart. This means that a missed dose of tizanidine can be taken whenever it is remembered or needed, as long as at least six to eight hours have passed.

How long can you take tizanidine?

There is no upper limit on how long people can take tizanidine. Healthcare providers will prescribe tizanidine for as long as it works and the side effects are tolerable. Because tizanidine can damage the liver, the prescriber will administer regular liver function tests. Tizanidine will be discontinued if the drug compromises the liver or if there are serious side effects. Because of drug interactions, tizanidine may need to be discontinued if certain other drugs are prescribed. Always check with your healthcare provider before beginning any new medication while taking tizanidine.

How do I stop taking tizanidine?

Do not stop taking tizanidine or reduce the dose without first talking to the prescriber or another doctor. The sudden discontinuation of tizanidine could cause withdrawal symptoms such as high blood pressure, racing heartbeat, hypertonia, and muscle rigidity. A doctor may need to prescribe a steadily decreasing dose if it’s time to quit taking tizanidine.

What is the maximum dosage for tizanidine?

The maximum daily dosage for tizanidine in adults is 36 mg per day, given in divided doses.

Can you overdose on tizanidine?

Do not take more tizanidine than prescribed. Do not take tizanidine more frequently than prescribed. A tizanidine overdose is serious and potentially life-threatening. Symptoms of a tizanidine overdose include extreme drowsiness, confusion, weakness, slow heart rate, low blood pressure, and slowed breathing. If a tizanidine overdose is suspected, immediately call a poison control center for medical advice or go to an emergency room.

What interacts with tizanidine?

The healthcare professional prescribing tizanidine must know about all prescription drugs, over-the-counter medications, and vitamins or supplements being taken to make sure that tizanidine is safely prescribed. Once on tizanidine, always check with your healthcare provider before taking any new medications.

Tizanidine is a powerful drug that affects nerves in the central nervous system. Some drug combinations greatly increase the risk of serious side effects of tizanidine, such as low blood pressure and slowed heartbeat. 

Because of these risks, drugs contraindicated (should never be used) for use with tizanidine include:

• The fluoroquinolone antibiotic ciprofloxacin

• The antidepressant drug fluvoxamine

• The ADHD medication Qelbree (viloxazine)

Healthcare providers will also avoid certain drugs because of the risks including:

• Other central nervous system (CNS) depressants such as alcohol, opioid pain medicines, benzodiazepines, tricyclic antidepressants, and medicines that help you sleep

• Oral contraceptives

• Heart rhythm drugs including amiodarone, propafenone, and verapamil

• Other fluoroquinolone antibiotics like levofloxacin 

• The stomach acid reducers famotidine and cimetidine

• The herpes drug acyclovir

• The asthma drug Zyflo (zileuton)

These combinations are to be avoided but aren’t strictly forbidden, for example, when no other alternative is available. Dosages may need to be adjusted to prevent problems. Healthcare providers will closely monitor the patient for potential side effects.

What happens when you mix tizanidine and alcohol?

Do not drink alcohol when taking tizanidine. Both cause a slowing down of the central nervous system. The combination will increase the sedative effects of both drugs such as drowsiness and lightheadedness—and can cause breathing to slow or even stop. Alcohol also increases the concentration of tizanidine in the blood, increasing the risk of sedation and other adverse effects.

Is it safe to take tizanidine during pregnancy?

There are no studies concerning the safety of tizanidine in humans during pregnancy. In animal studies, evidence of fetal harm and death occurred. Consult your healthcare provider if you are pregnant or planning to become pregnant.

Is it safe to take tizanidine while breastfeeding?

The FDA recommends that tizanidine not be given to women who are breastfeeding. No one has studied if tizanidine passes into breast milk or affects a nursing baby. However, animal studies have determined tizanidine is likely present in breast milk. There is a theoretical possibility of serious side effects such as sedation or low blood pressure in the nursing baby. In the end, a woman and her doctor should consult about the need to take tizanidine, weighing the risks and benefits.

Related resources for tizanidine dosages:

• Tizanidine, StatPearls

• Tizanidine adult dosing, Epocrates

• Tizanidine hydrochloride drug summary, Prescriber’s Digital Reference

• Zanaflex prescribing information, U.S. National Library of Medicine