Tizanidine: 7 things you should know
Medically reviewed by Carmen Fookes, BPharm. Last updated on Nov 6, 2019.
1. How it works
- Tizanidine relaxes muscles by dampening down nerve impulses that are sent from spasming muscles along nerve fibers to the brain.
- Tizanidine belongs to the class of medicines known as central alpha-2-adrenergic agonists. It also belongs to the group of medicines known as muscle relaxants.
- Effective at relaxing muscles (reduces muscles spasms).
- May be used on an as-needed basis.
- Generic tizanidine is available.
If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:
- Low blood pressure, drowsiness, dizziness, energy loss, and a dry mouth.
- Has been associated with hallucinations and rarely psychosis in approximately 3% of people.
- May not be suitable for people that rely on spasticity to sustain their posture and balance.
- May cause a drop in blood pressure when going from a sitting or lying down position to standing. This may increase the risk of falls.
- May affect a person's ability to drive or operate machinery. Alcohol should be avoided.
- May cause withdrawal symptoms such as high blood pressure and a fast heartbeat if stopped abruptly after regular extended dosing (decrease dose slowly under a doctor's advice).
- Not recommended to be taken by people with liver or kidney disease.
- Seniors may be more susceptible to the side effects of tizanidine.
- May interact with a number of other drugs including those metabolized by hepatic enzymes CYP1A2 (such as fluvoxamine, ciprofloxacin, some antiarrhythmics), and oral contraceptives. Alcohol increases the peak concentration of tizanidine and also the likelihood of side effects.
- Liver enzymes (specifically aminotransferase) should be monitored when starting treatment and for at least one month after the maximum dosage is achieved.
Notes: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. For a complete list of all side effects, click here.
- Capsules may be opened and the contents sprinkled on food.
- Taking with food increases absorption by 20% but slows time for effect. Can be taken with or without food, but should be dosed consistently (either with or without food).
- Take tizanidine exactly as directed. Do not increase the dosage without your doctor's advice. Tizanidine tablets and capsules are not directly interchangeable; a dosage adjustment may be necessary (talk with your doctor).
- Be careful when going from sitting or lying down position to standing as tizanidine may increase your risk of falls. Remove any fall hazards (such as loose rugs) from your home.
- Seek immediate medical advice if you experience any worrying side effects including hallucinations or allergic-type reactions.
- Do not stop taking tizanidine suddenly without your doctor's advice as high blood pressure and a fast heartbeat may result.
- Effects are dose-related (the bigger the dose, the stronger the effect, but the more noticeable any side effects are).
- Do not drink any alcohol while taking tizanidine.
- Do not take any other medication, including medicines brought over-the-counter, in addition to tizanidine, without first checking with your doctor or pharmacist first to make sure they are compatible.
6. Response and Effectiveness
The effects of tizanidine peak within 1-2 hours and start to wear off within 3 to 6 hours. Because of this short duration of effect, tizanidine may be dosed on an "as needed" basis during times when muscle spasms are at their most severe.
Medicines that interact with tizanidine may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with tizanidine. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.
Common medications that may interact with tizanidine include:
- anti-anxiety medications
- antidepressants, such as amitriptyline, imipramine, nortriptyline
- antihistamines that cause sedation, such as diphenhydramine
- HIV medications such as saquinavir
- medications that lower blood pressure, such as ACE inhibitors (eg, enalapril), barbiturates, beta-blockers (such as atenolol), or calcium channel antagonists (such as diltiazem)
- medicines that inhibit CYP1A2 enzymes such as cimetidine or rifampin
- opioid analgesics such as oxycodone and morphine
- other muscle relaxants such as methocarbamol
- sleeping pills, such as zolpidem
- some chemotherapy treatments
- some medications used to treat mental illness, such as clozapine and thioridazine
Alcohol may worsen the side effects of tizanidine such as drowsiness and dizziness.
Note that this list is not all-inclusive and includes only common medications that may interact with tizanidine. You should refer to the prescribing information for tizanidine for a complete list of interactions.
Tizanidine. Revised 07/2019. Drugs.com. https://www.drugs.com/ppa/tizanidine.html
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use tizanidine only for the indication prescribed.
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- Drug class: skeletal muscle relaxants
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Other brands: Zanaflex