Worst Pills, Best Pills

An expert, independent second opinion on more than 1,800 prescription drugs, over-the-counter medications, and supplements

Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: tizanidine (tye ZAN i dine)
Brand name(s): ZANAFLEX
GENERIC: available FAMILY: Drugs for Spasticity
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

Tizanidine caused fetal death and developmental retardation in animal studies. Because of the potential for serious adverse effects to the fetus, this drug should not be used by pregnant women.

Breast-feeding Warning

No information is available from either human or animal studies. However, it is expected that this drug is excreted in human milk, and because of the potential for adverse effects in nursing infants, you should not take this drug while nursing.

Facts About This Drug [top]

Tizanidine is approved by the Food and Drug Administration (FDA) for the management of spasticity in conditions such as multiple sclerosis and spinal cord injury. It has been available in Japan and Europe since 1985 for use as a short-term muscle relaxant.[1]

An April 2007 public advisory issued by the FDA said using tizanidine together with certain drugs (including fluvoxamine [LUVOX] and ciprofloxacin [CIPRO]), can result in drowsiness and extremely low blood pressure.[2]

Tizanidine...

Tizanidine is approved by the Food and Drug Administration (FDA) for the management of spasticity in conditions such as multiple sclerosis and spinal cord injury. It has been available in Japan and Europe since 1985 for use as a short-term muscle relaxant.[1]

An April 2007 public advisory issued by the FDA said using tizanidine together with certain drugs (including fluvoxamine [LUVOX] and ciprofloxacin [CIPRO]), can result in drowsiness and extremely low blood pressure.[2]

Tizanidine is related chemically to the blood-pressure-lowering drug clonidine (CATAPRES). Because tizanidine can lower blood pressure, patients should be cautious when using this drug in combination with blood pressure-lowering drugs. Even when used alone, patients may experience dizziness, lightheadedness, or fainting when getting up suddenly from a sitting or lying position because of the blood pressure-lowering effect of this drug.

Drowsiness was reported by almost half (48 percent) of patients taking tizanidine in clinical trials. In 10 percent of these cases, the drowsiness was severe.

A small percentage (about 5 percent) of patients participating in controlled clinical trials experienced liver function test (LFT) results greater than three times the upper limit of what is considered normal. This level of LFT elevation is an early indicator of possible liver toxicity. In postmarketing reports, the use of tizanidine has been associated with three deaths from liver failure. LFT monitoring should be done before and during the first six months of tizanidine treatment.[3]

Before You Use This Drug [top]

Tell your doctor if you have or have had:

  • kidney disease
  • allergy to tizanidine
  • liver disease
  • pregnancy or are breast-feeding

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Schedule regular visits with your doctor to check your progress.
  • Until you know how you react to this drug, do not drive or perform other activities that require alertness.
  • Do not drink alcohol or use other drugs that can cause drowsiness.
  • Chew sugarless gum, candy, or ice, or use a saliva substitute if you develop dryness in your mouth. If dryness continues more than two weeks, check with your doctor or dentist.
  • You may feel dizzy when rising from a lying or sitting position. When getting out of bed, hang your feet over the side of the bed for a few minutes, then get up slowly. When getting out of a chair, stay by the chair until you are sure that you are not dizzy.
  • Do not suddenly stop taking this drug without checking with your doctor to find out if you need to taper off.

How to Use This Drug [top]

  • If you miss a dose, take it if it is within an hour of the missed dose, but skip it if you don’t remember until later. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

alcohol, any blood-pressure-lowering medications, oral contraceptives, or phenytoin (DILANTIN).

Adverse Effects [top]

Call you doctor immediately if you experience:

  • nervousness
  • tingling, burning, or prickling sensations
  • fever
  • appetite loss
  • nausea or vomiting
  • yellow eyes or skin
  • skin sores
  • painful or burning urination
  • irregular heartbeat
  • unusual tiredness or weakness
  • chills, fever, or sore throat
  • black, tarry stools
  • bloody vomit
  • coldness
  • dry, puffy skin
  • weight gain
  • mood or mental changes, including false beliefs
  • hallucinations
  • kidney stones
  • seizures
  • fainting
  • cough
  • blurred vision
  • eye pain

Call your doctor if these symptoms continue:

  • anxiety
  • neck pain
  • unusual tiredness or weakness
  • back pain
  • constipation
  • depression
  • dizziness or lightheadedness
  • drowsiness or sleepiness
  • dry mouth
  • uncontrolled body movements
  • heartburn
  • diarrhea
  • stomach pain
  • vomiting
  • muscle spasms or weakness
  • increased sweating
  • sore throat
  • runny nose
  • skin rash
  • difficulty speaking
  • hair loss
  • arthritis
  • warm, swollen, and tender body areas
  • dry skin
  • difficulty swallowing
  • swelling of feet or lower legs
  • migraine headache
  • mood or mental changes, including agitation
  • unusual feeling of well-being
  • trembling or shaking
  • weight loss

Signs of overdose:

  • difficulty breathing

If you suspect an overdose, call this number to contact your poison control center: (800) 222-1222.

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • liver function tests

last reviewed June 30, 2021