Tizanidine Side Effects: Zanaflex Warnings

Last Updated: February 19, 2020

Although Zanaflex is an efficient drug for treating muscle spasms caused by multiple sclerosis or spinal cord injury, the patient might also experience some tizanidine adverse effects. Some side effects of Zanaflex are common and do not put the patient’s life in any danger, while others may need immediate medical attention.

What Are The Side Effects Of Tizanidine?

The common side effects of Zanaflex can be divided into short-term and long-term.

Asking the doctor the right questions, such as what Zanaflex is and what the possible side effects are, can help the patient know what to expect from this drug and how to handle adverse reactions.

Short-term side effects of tizanidine

  • Chills or fever
  • Chest pain
  • Burning or pain while urinating
  • Nausea or vomiting
  • Unusual tiredness
  • Diarrhea or constipation
  • Nervousness
  • Stomach pain
  • Dry mouth
  • Back pain
  • Muscle weakness
  • Dizziness
  • Drowsiness
  • Sweating
  • Back pain

Long term effects of tizanidine

  • Depression
  • Liver disease
  • Kidney disease
  • Weight gain
  • Joint pain

Can Zanaflex Side Effects Cause Death?

There are some situations when the side effects of Zanaflex can be life-threatening. The patient might have an allergic reaction to tizanidine, resulting in itching, vomiting, trouble breathing, anxiety, and even anaphylaxis leading to death.

One of the tizanidine contraindications is combining it with drugs that can slow down breathing or cause sleepiness. The patient should inform the doctor before taking prescription cough medicine, narcotic pain medicine, sleeping pills, medicine for seizures, depression or anxiety, or muscle relaxers.

In some patients, tizanidine might cause an irregular heartbeat, known as QT prolongation, which can be life-threatening. The condition can cause seizures, fainting, and even sudden death. The patient should tell the doctor if they know themselves at risk for heart rhythm problems.

woman fainting on the street

Tizanidine used for its high side effect, when combined with other CNS depressants, can result in fatality. Combining such drugs can lead to an intensification of side effects, which, if not quickly addressed, can lead to drowsiness, lethargy, confusion, hypotension, bradycardia, respiratory depression, and coma. In such situations, immediate medical care for drug abuse is required.

Does Tizanidine Make One Sleepy Or Tired?

Zanaflex can cause tiredness, sleepiness, drowsiness, dizziness, a delay in reactions, lightheadedness, and unsteadiness, among others. That is why the patient should be informed on how to react in case they experience such side effects and to avoid driving, using machines, or do any activity that might be dangerous in such a situation.

Zanaflex drug class is alpha-2-adrenergic agonists, known to cause sleepiness and sedation by blocking neurotransmitter norepinephrine, which is necessary for arousal. The patient should inform the doctor if they experience unexplained or extreme tiredness or sleepiness.

Does Tizanidine Affect Weight?

Zanaflex weight gain is possible. The doctor will keep a close eye if this occurs, by closely monitoring any change in weight comparing all the patient’s past medical appointments. The doctor will ask about any changes in the patient’s exercise or eating habits and do a physical exam to see if the change in weight does not have a different cause, such as a pregnancy or retaining fluids.

If the drug causes weight gain, the doctor might recommend the patient a different medicine. This happens when the patient has gained a lot of weight, which can affect the health of the individual.

Does Tizanidine Lower Blood Pressure?

Zanaflex might lead to a dangerous decrease in blood pressure, causing fainting or dizziness. To prevent this risk, the doctor will prescribe the lowest possible dose of tizanidine 2mg, which is still efficient to the patient. If the individual is already under treatment with drugs that lower blood pressure, their blood pressure will be checked more often.

woman measuring blood pressure

Possible Signs Of An Allergic Reaction To Zanaflex

Zanaflex might cause dangerous allergic reactions, including anaphylaxis, which requires immediate medical attention. The patient should call the doctor as soon as they experience allergic tizanidine side effects such as trouble breathing, itching, a rash, swelling of the face, hands, lips or tongue, or trouble swallowing. Although a severe Zanaflex allergic reaction is rare, the patient should be cautious and seek help immediately.

Variables That Affects Side Effects Emergence

  • Allergy to the drug
  • Alcohol increases the side effects of the drug
  • Not respecting the tizanidine contraindications and combining it with other drugs
  • Pre-existing health conditions such as decreased liver or kidney function
  • Age of the patient. In some older people, the kidneys do not function properly, processing the drug more slowly meaning Zanaflex will stay in the body for a longer time increasing the risk of side effects
  • Taking too much Zanaflex may lead to symptoms of an overdose
  • Stopping the drug suddenly increases the chances of withdrawal symptoms
  • Types of intake – the tablets and capsules are absorbed differently
  • Individual tolerance
  • If the medication is taken with food or without. The patient can choose either option but should be consistent in the way of administering Zanaflex

Precautions To Prevent Side Effects

  • Start tizanidine at the lowest possible dose and gradually increase it
  • Carefully follow the doctor’s instructions when taking this drug
  • Avoid taking more than 36 mg a day
  • Have regular doctor checks, especially in the first weeks on Zanaflex
  • Do not take tizanidine with fluvoxamine or ciprofloxacin
  • Avoid getting up too quickly from a sitting or lying position to avoid side effects of Zanaflex such as lightheadedness, dizziness or fainting
  • Tell the doctor right away if experiencing dark urine, pale stools, pain in the upper stomach, nausea, vomiting, decrease in appetite or yellow skin or eyes, as these might be signs of a severe liver problem
  • Use sugar-free gum or candy, saliva substitute or melt pieces of ice in the mouth to relieve tizanidine dry mouth
  • Avoid taking tizanidine together with other CNS depressants such as antihistamines, sedatives, medicine for cold, sleeping pills, tranquilizers, barbiturates, prescription narcotics or pain medicine, other muscle relaxants, barbiturates, anesthetics (including dental) or medicine for seizures
  • This drug should not be stopped suddenly to avoid any possible withdrawal symptoms

Coping With Zanaflex Addiction

Some patients might become addicted to sedation, which is one of the tizanidine side effects, and to the tizanidine high when combined with other medications such as benzos or baclofen, or with alcohol. The treatment for patients dealing with tizanidine addiction is handled in specialized facilities for addicts, under the continuous supervision of skilled medical professionals.

Page Sources

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  2. Henney HR, Chez M. Pediatric safety of tizanidine: clinical adverse event database and retrospective chart assessment. Paediatr Drugs. 2009;11(6):397-406. https://www.ncbi.nlm.nih.gov/pubmed/19877725
  3. Farkas S, Berzsenyi P, Kárpáti E, Kocsis P, Tarnawa I. Simple pharmacological test battery to assess efficacy and side effect profile of centrally acting muscle relaxant drugs. J Pharmacol Toxicol Methods. 2005 Sep-Oct;52(2):264-73. https://www.ncbi.nlm.nih.gov/pubmed/16125625

Published on: February 19th, 2020

Updated on: February 19th, 2020


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