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Tizanidine Side Effects

In Summary

Commonly reported side effects of tizanidine include: bradycardia, dizziness, drowsiness, hypotension, asthenia, fatigue, and xerostomia. Other side effects include: constipation, and increased liver enzymes. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to tizanidine: oral capsule, oral tablet

Along with its needed effects, tizanidine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking tizanidine:

More common
  • Chest pain or discomfort
  • fever or chills
  • nausea or vomiting
  • nervousness
  • pain or burning while urinating
  • unusual tiredness
Less common
  • Blurred vision
  • flu-like symptoms
  • irregular heartbeat
  • itching skin
  • kidney stones
  • right upper stomach tenderness
  • seeing things that are not there
  • shortness of breath
  • weight gain
Incidence not known
  • Continuing vomiting
  • general feeling of tiredness or weakness
  • headache
  • light-colored stools

Get emergency help immediately if any of the following symptoms of overdose occur while taking tizanidine:

Symptoms of overdose
  • Blurred vision
  • change in consciousness
  • chest pain or discomfort
  • confusion
  • decreased awareness or responsiveness
  • difficult or troubled breathing
  • dizziness, faintness or lightheadedness when getting up from a lying position
  • irregular, fast or slow, or shallow breathing
  • lightheadedness, dizziness, or fainting
  • loss of consciousness
  • pale or blue lips, fingernails, or skin
  • severe sleepiness
  • sleepiness or unusual drowsiness
  • slow or irregular heartbeat
  • sweating
  • unusual tiredness or weakness

Some side effects of tizanidine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Dizziness or lightheadedness, especially when getting up from a lying or sitting position
  • drowsiness
  • dry mouth
  • fatigue
  • sleepiness
  • weakness
Less common

For Healthcare Professionals

Applies to tizanidine: oral capsule, oral tablet


The most frequently reported adverse reactions include dry mouth, somnolence/sedation, asthenia, and dizziness.[Ref]

Nervous system

Very common (10% or more): Somnolence (up to 48%), dizziness (up to 16%)
Common (1% to 10%): Speech disorder, dyskinesia
Frequency not reported: Headache, ataxia, dysarthria
Postmarketing reports: Convulsion, paresthesia, tremor[Ref]


Very common (10% or more): Dry mouth (up to 49%)
Common (1% to 10%): Vomiting, constipation
Rare (0.01% to 0.1%): Nausea, gastrointestinal disorder
Frequency not reported: Abdominal pain, loss of appetite[Ref]


Common (1% to 10%): Liver test abnormality
Very rare (less than 0.01%): Hepatic failure
Frequency not reported: Hepatotoxicity
Postmarketing reports: Hepatitis[Ref]


Common (1% to 10%): Bradycardia, hypotension, tachycardia
Postmarketing reports: Syncope, ventricular tachycardia, QT prolongation[Ref]


Common (1% to 10%): Amblyopia
Frequency not reported: Accommodation disorder[Ref]


Frequency not reported: Pruritus
Postmarketing reports: Stevens Johnson Syndrome, exfoliative dermatitis, rash[Ref]


Common (1% to 10%): Fatigue
Frequency not reported: Drug withdrawal reactions including rebound hypertension, tachycardia, and hypertonia[Ref]


Common (1% to 10%): Urinary tract infection, urinary frequency[Ref]


Common (1% to 10%): Pharyngitis, rhinitis[Ref]


Frequency not reported: Anaphylaxis, hypersensitivity reactions
Postmarketing reports: Anaphylactic Reaction[Ref]


Common (1% to 10%): Infection, flu syndrome[Ref]


Rare (0.01% to 0.1%): Muscular weakness
Postmarketing reports: Arthralgia[Ref]


Common (1% to 10%): Nervousness
Rare (0.01% to 0.1%): Hallucinations, insomnia, sleep disorders
Frequency not reported: Confusional state
Postmarketing reports: Depression[Ref]


1. "Product Information. Zanaflex (tizanidine)." Acorda Therapeutics, Hawthorne, NY.

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

Some side effects of tizanidine may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

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