What is Zanaflex: Uses, Dosage, Side Effects, and Precautions

Last Updated: May 14, 2024

Roger Weiss Authored by Roger Weiss, MD
David Levin Reviewed by David Levin
0 sources cited

People suffering from muscle spasms and pains due to multiple sclerosis, brain/spinal cord injury, or stroke can find relief by taking Zanaflex.

Zanaflex is the brand name for Tizanidine, a short-acting skeletal muscle relaxant. While it’s an effective medication for muscle cramping and tightness, caution must be observed when taking it to avoid severe side effects.

Read on to learn more about Zanaflex, its uses, usual dosage, side effects, and safety precautions when taking it.

What is Tizanidine?

Trade name: Zanaflex®

Generic name: Tizanidine

Tizanidine, is a centrally acting alpha-2 adrenergic agonist, secured FDA approval for medical use as a short-term management muscle relaxant specifically designed to address muscle spasms and heightened muscle tone associated with multiple sclerosis, spinal cord injuries, and certain neurological disorders.

Its mechanism of action involves suppressing excessive nerve signals in the spinal cord, resulting in muscle relaxation. Healthcare professionals prescribe Tizanidine when other treatments may not be suitable or have proven ineffective.

What is Zanaflex Used for?

Physicians prescribe Zanaflex (Tizanidine) to people with multiple sclerosis, stroke, injuries, and chronic neck and lumbosacral neuralgia to alleviate the pain due to muscle spasms.

Zanaflex is available as a tablet or capsule. The two are bioequivalent, meaning they have identical active ingredients (Tizanidine Hydrochloride) and provide the same desired therapeutic outcome to the patient.

This drug slows down the spinal nerve, inhibiting the release of muscle pain sensation to the brain, allowing the muscles to relax and terminate the spasms.

Here are some other uses of Zanaflex (Tizanidine):

  • Back pain: Some people take Zanaflex (in low doses) as a muscle relaxant to alleviate upper or lower back pain.
  • Amyotrophic Lateral Sclerosis (ALS):  ALS is a condition in which the voluntary muscle neurons die, causing muscle stiffness and twitching. Zanaflex can be used as a muscle relaxant for ALS.
  • Migraines: Zanaflex blocks pain signals to the brain, reducing the pain from migraine.
  • Anxiety: As a muscle relaxant, Zanaflex produces the same effects as a sedative that can provide relaxation during anxiety situations.

What do tizanidine pills look like?

The best way to identify Tizanidine pills is by the colors, shapes, and manufacturer names or numbers embossed on the tablets. Some Tizanidine tablets are scored, and the capsules might be in different colors. This article may help you identify the different presentations of Tizanidine: What Does Tizanidine Look Like? Zanaflex Pill Identifier

Composition of Zanaflex Drug

To further understand how the drug works, let’s discuss what Zanaflex is made of.

A Zanaflex tablet consists of:

  • Tizanidine hydrochloride: the drug’s active ingredient that blocks nerve pain reception to the brain.
  • Stearic acid: an inactive ingredient; acts as tablet lubricant for oral medications
  • Silicon dioxide colloidal: an inactive ingredient that allows powder to flow when the tablet is taken.
  • Microcrystalline cellulose: an inactive ingredient that quickens tablet disintegration.
  • Anhydrous lactose: an inactive ingredient, improves the drug’s water solubility (“wetness”).

On the other hand, a Zanaflex capsule consists of:

  • Tizanidine hydrochloride
  • Hydroxypropyl methylcellulose: inactive ingredient; a thickening agent added in capsules
  • Sugar spheres: inactive ingredient; acts as a base for which the drug is coated.
  • Silicon dioxide: inactive ingredient; aids in flowing materials
  • Titanium dioxide: inactive ingredient; protects the capsule from light degradation.
  • Gelatin and colorants

Contrary to common misconception, Zanaflex is not a combination of two other drugs: Xanax and Flexeril. Zanaflex’s composition is completely different from those of these medications.

How To Take Zanaflex?

You must take Zanaflex only if your doctor prescribes it. Otherwise, don’t consume the drug, as it may cause severe side effects.

Recommended Zanaflex Tizanidine Dosage

The dosage of Zanaflex will be based on your current health condition and the other medications you’re using.

But usually, the doctor’s starting dose is 2 mg of Tizanidine. If you are wondering, ‘How long does tizanidine last?’  The drug effect usually peaks at around 1 to 2 hours after consumption and dissipates between 3 to 6 hours. For people asking, ‘How often can I take tizanidine?’ The answer is that you can take the drug every 6 to 8 hours, but you must keep a maximum of 3 doses only in 24 hours.

After 1 to 4 days, the dosage can be increased from 2 to 4 mg. Most people feel better with the tizanidine 4 mg tablet than with the Tizanidine 2 mg tablet. The daily dose of Tizanidine must not exceed 36 mg.

Can You Take Zanaflex With or Without Food?

Zanaflex can be taken with or without food, but you must always take it in the same manner.

For instance, if the doctor prescribes you to take Zanaflex immediately after a meal, you must follow this regimen throughout the medication period unless the physician instructs you to change it.

Another usual question, besides taking Zanaflex with or without food, is if there is any difference between consuming a tizanidine capsule vs tablet. Well, the answer is that it should have no impact on the medication’s effect.

The effect of Zanaflex might be different depending on whether you take it with an empty or full stomach. However, consuming food before taking the drug can increase the absorption of the tablet or capsule.

You can clarify with your doctor how to take the medicine for the best effect.

What are the Potential Side Effects of Zanaflex?

There’s a reason why doctors prescribe small doses of Zanaflex to first-time users. While Zanaflex is an effective muscle relaxant, it can induce these common side effects:

  • Weakness or tiredness
  • Dry mouth
  • Nervousness
  • Blurred vision
  • Chills and other flu-like symptoms
  • Nausea and vomiting
  • Stomach pain, constipation, diarrhea
  • Tingling sensation in the hands, arms, and feet
  • Sore throat
  • Runny nose
  • Pain while urinating

Tizanidine’s side effects on blood pressure are often a major concern, as low blood pressure may result from the use of Zanaflex. This is why a person might experience drowsiness and tiredness. Hence, constant BP monitoring is vital for people under Tizanidine medication.

Meanwhile, if you experience these tizanidine side effects (which are uncommon), you must immediately visit your doctor:

  • Hallucinations and confusions
  • Yellowing of the eyes
  • Difficulty breathing
  • Low appetite and drop in weight

Warnings and Precautions When Taking Zanaflex

As with other medication drugs, Zanaflex must be used with caution to ensure that it will not risk one’s health.

Safety Precaution When Taking Zanaflex

Remember these precautionary measures when using Zanaflex:

  • Drowsiness and low mental alertness are common side effects of Zanaflex. Hence, it’s not advisable to drive, operate a machine, or perform extraneous tasks upon taking this medication.
  • Do not suddenly stop your intake of Zanaflex, as it may cause rebound hypertension and other withdrawal symptoms. Discuss with your doctor if you want to discontinue your Zanaflex medication, as withdrawal from tizanidine may cause you harm.
  • Do not take two Zanaflex pills if you miss a dose. Only take the dose that you’re supposed to take.
  • For people with renal impairment (kidney failure) or hepatic impairment (liver failure) but who need high doses of Zanaflex, individual drug dosage must be increased instead of the frequency of drug intake.

Potential Health Risks of Using Zanaflex

While Zanaflex is completely safe to use, it can still pose serious health consequences due to misuse or prolonged use.

Zanaflex Overdose

Tizanidine overdose can be a serious medical emergency when the person consumes higher doses of Zanaflex than what is intended. Overdose can be intentional (when the patient wants to get more “relief” from muscle stiffness) or accidental (when the patient takes the wrong dosage).

Some signs of overdose include:

  • Drowsiness
  • Weakness
  • Light-headedness
  • Confusion or hallucination
  • Slow heart rate
  • Sudden collapse

Immediate medical care is needed for a person who overdosed on Zanaflex. No antidote can counter Tizanidine overdose, and the only way to treat it is through a specialized detoxification process.

Heart-related problems

Prolonged use of Tizanidine can cause heart disorders. For instance, the drug can cause QT prolongation, a life-threatening condition characterized by irregular heartbeats, in some patients.

There’s also a 2018 study that documented the case of a healthy, 37-year-old man who suffered from Bradycardia (unusually slower heart rate than normal rate) after beginning his Tizanidine/loxoprofen combination therapy for neck pain.

The occurrence of Bradycardia is considered a rare side effect of Tizanidine, but in the case of the patient, the combination of Tizanidine with loxoprofen was suspected as the culprit.

Acute Liver Injury

A 2017 study reported cases of Tizanidine use association with acute liver(hepatic) injury. For instance, a 55-year-old woman with multiple sclerosis and lower limb muscle spasms developed jaundice (red blood cells dying and going to the liver, manifesting with yellowish eyes and skin) 4 months after she started her Tizanidine treatment.

Severe Allergic Reaction

Tizanidine can cause allergic reactions in some patients, causing itching, swelling of the tongue or throat, dizziness, and breathing difficulty. Seek immediate medical care by calling 911 when an allergic reaction strikes upon consumption of Tizanidine.

Potential Health Risks of Zanaflex To Other Groups

Some people must take extra precautions if they use Tizanidine.

Pregnant Women: Research with animals has shown that Tizanidine use can harm the fetus. While this study hasn’t been replicated yet in humans, Tizanidine is still not commonly prescribed for pregnant women. The drug is an FDA pregnancy category C medication, which means that it should be taken only upon considering that potential benefits from the use can outweigh the risks.

For Breastfeeding Women: Tizanidine is considered a lipid-soluble drug, which means there’s a slight chance of it being present in the breast milk and affecting infant growth. Thus, Tizanidine is not recommended for lactating women.

For Children: The effects of Tizanidine on people under 18 still need further scientific exploration. Hence, the drug must not be used for young people.

For Old People: Older people tend to have weaker kidneys and liver, leading to slower drug absorption. This means that the drug stays in the body longer, which can aggravate side effects. Therefore, the use of Tizanidine can be riskier for this age group.

Beat Zanaflex Dependence and Addiction

Tizanidine can be an addictive drug due to prolonged use. If your loved one has a Zanaflex addiction, you can still help them by connecting with treatment centers that can provide them with the cure to a better life.

Addiction Resource can help you find top rehab and intervention centers to overcome drug addiction. Call (800) 913-1755 today.

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Page Sources

  2. National Institute of Health: TIZANIDINE HCL- tizanidine hcl tablet
  3. National Institute of Health: ZANAFLEX - tizanidine hydrochloride capsule
  4. National Library of Medicine: Bioavailability and Bioequivalence in Drug Development
  5. National Library of Medicine: Tizanidine
  6. Sage Journals: Irreversible profound symptomatic bradycardia requiring pacemaker after tizanidine/loxoprofen combination therapy: a case report
  7. ScienceDirect
  8. Ghanavatian, S. (2023, August 28). Tizanidine. StatPearls - NCBI Bookshelf.

Retrieved on February 05, 2024

Published on: February 19th, 2020

Updated on: May 14th, 2024

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