Tizanidine (Muscle Relaxant) Uses & Side Effects

Tizanidine hydrochloride (brand name Zanaflex) is a prescription medication that belongs to a group of drugs called skeletal muscle relaxants or simply muscle relaxants. It is used to treat muscle spasms or muscle spasticity causing symptoms such as muscle pain, stiffness, and muscle tightness. Tizanidine is often prescribed to relieve the increased muscle tone and muscle spasms in people with muscle spasticity, multiple sclerosis, and spinal cord injury.

Please continue reading to learn more about tizanidine, including its uses, side effects, risks, and warnings.

How does tizanidine work as a muscle relaxer?

Tizanidine stimulates alpha-2 adrenergic receptors in the central nervous system, thus inhibiting the release of norepinephrine. Norepinephrine is a brain chemical that increases the force of skeletal muscle contraction. By inhibiting the release of norepinephrine, tizanidine helps reduce muscle spasticity leading to reduced muscle tone and muscle relaxation.

What are the common side effects of tizanidine?

Possible side effects of tizanidine include dizziness, drowsiness, weakness, lack of energy, dry mouth, vomiting, constipation, nervousness, blurred vision, painful urination, urinary tract infection, abnormal liver function tests, flu-like symptoms, runny nose, sore throat, speech problems, vision changes, and uncontrolled muscle movements.

Call your doctor for medical advice if these side effects are worsening or do not go away after a few days when your body has had a chance to get used to the medicine.

What is the serious adverse effect of tizanidine therapy?

Call 911 and seek emergency medical attention for a life-threatening situation. Call your doctor if you notice any worsening or serious side effects from tizanidine.

Severe allergic reactions to tizanidine are rare but can include life-threatening reactions like anaphylaxis (throat closing). Call 911 if this happens. Also, call your doctor or seek emergency medical help if you develop adverse reactions such as skin rash, hives, itching, swelling of your lips or tongue, or difficulty breathing while on tizanidine.

Serious side effects of tizanidine include:

Hallucinations, confusion, and delusions;
Very low blood pressure: light headed feeling, like you may faint;
Significant sedation: feeling weak, shallow breathing, lethargy, weakness;
Liver function impairment: jaundice (yellowing of the skin and the whites of the eyes), fatigue, abdominal pain, and unusual bleeding or bruising;

Seek emergency medical attention if you develop these serious side effects of tizanidine.

In case of an overdose of tizanidine, call your local poison control center or the national poison control center at 1-800-222-1222. Overdose symptoms may include drowsiness, dizziness, tiredness, slow heartbeat, weak or shallow breathing, and loss of consciousness.

How should I take tizanidine?

Tizanidine is available in the following dosage forms:

Oral tablets: 2 mg, 4 mg
Oral capsules: 2 mg, 4 mg, 6 mg

The recommended starting dose is 2 mg or 4 mg every 6-8 hours. Your healthcare provider can titrate the dose by 2 to 4 mg increments every 2 to 4 days based on your response and tolerability of side effects.

The dosing interval is 6 to 8 hours, but you should not exceed 36 mg or 3 doses in 24 hours.

Take tizanidine capsules or tablets exactly as prescribed by your healthcare professional. You can take this medicine with or without food, but you should do so consistently, either always with or without food. Going from taking tizanidine with food to taking it without food and vice versa can affect therapy effectiveness or increase tizanidine's side effects.

Read the prescription label and follow your doctor’s instructions carefully. Do not change the dose, dosing interval, or duration of treatment without your doctor’s approval.

If you have trouble swallowing pills, talk to your doctor about opening the capsules and sprinkling the contents on a soft food such as applesauce. You should discuss the plan with your doctor before implementing it.

Do not substitute tizanidine tablets for tizanidine capsules or vice versa. These formulations are not interchangeable. Check your medication when you pick up your prescription, and make sure you receive the dosage form you were prescribed (tablets or capsules).

Remember that food can increase blood levels of tizanidine tablets, while blood levels of tizanidine capsules are decreased.

Your doctor may start you on a lower dose of tizanidine and gradually increase the dose based on your response to the medication. If you wish to stop taking this medicine, tell your doctor. Do not stop the medicine suddenly, as it can cause withdrawal symptoms such as nausea, vomiting, fast heartbeat, high blood pressure, and muscle tightening, especially if you have been on tizanidine at high doses or for a long time. Your doctor will tell you how to lower the dose slowly.

If you miss a dose of tizanidine, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take your next scheduled dose. Do not take a double dose or extra medicine to make up for a missed dose.

What precautions should I take on tizanidine?

Before starting tizanidine, tell your doctor if you have ever had an allergic reaction to tizanidine or any other medications.

Give your doctor and pharmacist a complete list of all your medications, including prescription drugs, over-the-counter medicines, dietary supplements, and herbal products. This will help avoid potential drug interactions between tizanidine and your other drugs. Tizanidine can interact with certain medications such as oral contraceptives (birth control pills), blood pressure medications, anxiety medications, antiviral drugs, certain antibiotics, sedatives, sleeping pills, tranquilizers, and seizure medications.

Tell your doctor if you have a medical history of kidney disease or liver disease.

Tizanidine can cause side effects such as drowsiness and dizziness. Do not drive, operate heavy machinery, climb ladders, or do any other hazardous activity until you know how this medicine affects you. Avoid drinking because alcohol can make these tizanidine side effects worse.

You may experience a light headed feeling and dizziness when you get up from a sitting or lying position to standing after taking tizanidine. This is more likely to occur when you first start the medication or after an increase in dosage. Get up slowly from bed and rest your feet on the floor for a few minutes to lower your risk of falls. Also, keep in mind that tizanidine can reduce muscle tone. Be careful during activities in which you rely on muscle tone for balance.

Before starting tizanidine, tell your doctor if you are pregnant or nursing an infant with breast milk. Call your doctor if you become pregnant while taking this medicine.

What are the possible risks associated with taking tizanidine?

HYPOTENSION

Tizanidine can cause hypotension (low blood pressure), especially in those 65 years of age and older and those taking blood pressure medications. Do not take tizanidine with an antidepressant called fluvoxamine or the antibiotic ciprofloxacin, as this can cause a dangerous drop in blood pressure. This drop in blood pressure can also occur by getting up too fast from sitting or lying down. Stand up slowly from a sitting or lying position and try to hold on to the head of the bed or a side table to prevent falls due to dizziness.

LIVER INJURY

Tizanidine can cause liver damage. If you have abnormal liver function tests or a history of liver problems, your doctor may advise you not to take this medicine. If you are on long-term treatment with tizanidine, your provider may order regular blood tests to check liver function.

SEDATION

Tizanidine can cause sleepiness and decrease your ability to focus and concentrate. The risk of these tizanidine side effects is higher in older adults aged 65 and above, those who drink alcohol or use illicit drugs, and people taking other medications that can also cause drowsiness. Avoid alcohol while on tizanidine. Do not drive or do any activities that require you to be fully alert until you know how tizanidine affects you.

HALLUCINATIONS

Rarely, tizanidine can trigger hallucinations (seeing or hearing things that are not there). This side effect of tizanidine usually disappears when you stop the medicine. Tell your doctor if this happens. They may switch you over to another muscle relaxant.

KIDNEY PROBLEMS

People with a history of kidney disease should take tizanidine with caution. This medication is metabolized (processed) by the kidneys. If the kidneys are not working properly, it can cause a buildup of the drug in the body, increasing the risk of side effects. Your doctor may prescribe a low dose of tizanidine if you have kidney problems.

Who should not take tizanidine?

Anyone with a history of an allergic reaction to tizanidine should not take this medicine. Tizanidine is also not a safe option for people with liver disease. Also, people taking certain drugs, such as the antidepressant fluvoxamine (Luvox) or the antibiotic ciprofloxacin, should not take tizanidine due to potentially dangerous interactions that can lead to low blood pressure.

Note: This drug information should not be used as a substitute for professional medical advice. Call your doctor if you have further questions about tizanidine uses and side effects.

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