What is Zanaflex: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 31, 2020

Zanaflex is a brand-name muscle relaxant currently unavailable in the U.S. and possibly discontinued by its manufacturer. Its active ingredient, tizanidine, is widely available as a generic to treat muscle spasms due to serious medical conditions such as multiple sclerosis or central nervous system injuries. Healthcare professionals are still likely to prescribe generic tizanidine as “Zanaflex,” but pharmacists know to substitute the generic version.

Zanaflex overview

BRAND NAMES:

  • Zanaflex

Generic Names:

  • Tizanidine HCI

Uses:

  • Treats muscle spasticity.

Therapeutic Classes:

  • Centrally-acting skeletal muscle relaxant, alpha-2 adrenergic receptor agonist

Forms:

  • Capsule, tablet

How it’s taken:

  • By mouth

What is Zanaflex used for?

Tizanidine treats muscle spasms in people with neurologic disorders such as multiple sclerosis, spinal cord injury, or brain injury. Because of side effects, doses are recommended to be taken when people wish to engage in important activities.

What form(s) does Zanaflex come in

  • Capsule

    • 2 mg

    • 4 mg

    • 6 mg

    • Tablet

    • 4 mg

What are common Zanaflex doses?

  • For muscle spasticity in adults: 2–4 mg taken as needed in doses spaced six to eight hours apart (maximum daily dose: three doses not exceeding 36 mg total).

Common Zanaflex prescriptions

  • Zanaflex
    10 tablets bottle

  • Zanaflex
    15 tablets bottle

  • Zanaflex
    20 tablets bottle

  • Zanaflex
    30 capsules bottle

  • Zanaflex
    30 tablets bottle

  • Zanaflex
    45 tablets bottle

  • Zanaflex
    60 capsules bottle

  • Zanaflex
    90 tablets bottle

  • Zanaflex
    2mg capsule

  • Zanaflex
    4mg capsule

  • Zanaflex
    6mg capsule

  • Zanaflex
    4mg tablet

How to take Zanaflex

  • Follow all the prescriber’s instructions. The dose may change during treatment. 

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

  • Take a dose when needed unless directed otherwise by the prescriber. Because the effects last a short time, take the dose before activities that require relief from muscle spasms.

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

  • Do not take more than three doses in a day.

  • Zanaflex can be taken with food or on an empty stomach but always take it the same way.

  • Store Zanaflex in a closed, child-proofed container at room temperature (59°F to 86°F).

  • Keep Zanaflex out of the reach of children.

What to do if you miss a dose of Zanaflex

  • Take a missed dose when remembered. 

  • If it is almost time for your next dose, wait until then and take a regular dose. 

  • Do not take extra medicine to make up for a missed dose.

Zanaflex contraindications

Zanaflex warnings

  • Tell any doctor or other healthcare provider who treats you that you are taking Zanaflex.

  • Zanaflex is a powerful medication, so the prescriber needs regular examinations and blood tests to monitor treatment and side effects. Keep all appointments.

  • Tell the prescriber if you are pregnant, breastfeeding, or have kidney or liver problems.

  • Tell the prescriber if you smoke.

  • Tizanidine can cause serious problems, including:

    • Liver damage

    • Very low blood pressure

    • Withdrawal symptoms include muscle rigidity, muscle spasms, racing heartbeats, and high blood pressure

  • Tizanidine can cause drowsiness and dizziness. Avoid driving or other potentially hazardous activities until you know how this medicine affects you. 

  • Do not stop taking tizanidine until talking to the prescriber, especially if the doses are large or have been taken for a long time. The doctor may need to slowly decrease the dose to safely discontinue the drug.

Zanaflex interactions

  • Before taking Zanaflex, make sure the prescribing healthcare provider knows about all prescription drugs, over-the-counter medications, and supplements being taken.

  • Tell other healthcare professionals about tizanidine before they prescribe new medications.

  • Never take tizanidine along with ciprofloxacin (an antibiotic) or fluvoxamine (an antidepressant).

  • Tizanidine can cause serious side effects when combined with certain drugs, particularly:

  • Avoid alcohol when taking tizanidine.

  • Avoid smoking. 

Find out more about tizanidine interactions to avoid here.

Zanaflex side effects

Serious side effects

Talk to a doctor if you notice any signs or symptoms of a possible serious side effect, including:

  • Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes

  • Slow heartbeat

  • Lightheadedness, dizziness, fainting, low blood pressure

  • Seeing or hearing things that aren’t there

  • Blistering, peeling, or red skin rash

  • Allergic reaction: Itching, hives, rash, swelling in your face or hands, swelling or tingling in your mouth or throat, throat tightness, chest tightness, trouble breathing, 

Less serious side effects

  • Sleepiness

  • Dry mouth

  • Weakness

  • Dizziness

  • Low blood pressure

  • Slowed heart rate

  • Infection

Sources:

Subscribe to our savings newsletter

Health education, drug info, wellness & more

By clicking 'Subscribe', I agree to SingleCare's Terms & Conditions.