What is dantrolene?

Dantrolene is a muscle relaxant. It works by directly affecting the ability of your muscles to contract (stiffen).

Dantrolene is used to treat muscle spasticity (stiffness and spasms) caused by conditions such as a spinal cord injury, stroke, cerebral palsy, or multiple sclerosis.

Dantrolene is also used to prevent the development of malignant hyperthermia (a rapid rise in body temperature) and stiff muscles caused by anesthesia during or after surgery.

Although not approved by the FDA for these uses, dantrolene has also been used to treat exercise-induced muscle pain, neuroleptic malignant syndrome, and heat stroke.

Dantrolene may also be used for purposes other than those listed in this medication guide.


Do not take dantrolene if you have a liver disease such as hepatitis or cirrhosis.

Before taking this medication, tell your doctor if you

  • have a breathing or lung disease,
  • have heart disease, or
  • have had liver disease in the past.

You may need special monitoring during your therapy with dantrolene if you have any of these conditions.

Dantrolene is in the FDA pregnancy category C. This means that it is not known whether dantrolene will harm an unborn baby. Do not take dantrolene without first talking to your doctor if you are pregnant.

It is also not known whether dantrolene passes into breast milk. Do not take dantrolene without first talking to your doctor if you are breast-feeding a baby.

Dantrolene is not approved for use by children younger than 5 years of age.

Use caution when driving, operating machinery, or performing other hazardous activities. Dantrolene may cause dizziness or drowsiness. If you experience dizziness or drowsiness, avoid these activities.

Use alcohol cautiously. Alcohol may increase drowsiness and dizziness while you are taking dantrolene.

Weakness in grip, leg muscles, and swallowing may occur. Use caution, especially when climbing stairs and eating meals, to prevent falls and choking.

Avoid prolonged exposure to sunlight. Dantrolene may increase the sensitivity of your skin to sunlight. Use a sunscreen and wear protective clothing when exposure to the sun is unavoidable.

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Seek emergency medical attention.

Symptoms of a dantrolene overdose include muscle weakness, drowsiness, unconsciousness, vomiting, and diarrhea.

Take the missed dose as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take only your next regularly scheduled dose. Do not take a double dose of this medication.

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Side effects

If you experience any of the following serious side effects, stop taking dantrolene and seek emergency medical attention:

  • an allergic reaction (difficulty breathing; closing of your throat; swelling of your lips, tongue, or face; or hives);
  • a rash or itching;
  • black, bloody, or tarry stools or severe diarrhea;
  • yellow skin or eyes; or
  • seizures.

Other, less serious side effects may be more likely to occur. Continue to take dantrolene and talk to your doctor if you experience

  • drowsiness, dizziness, weakness or fatigue;
  • diarrhea, constipation, upset stomach, or decreased appetite;
  • difficulty swallowing (use caution to prevent choking);
  • headache or insomnia;
  • depression or confusion;
  • blurred or abnormal vision; or
  • increased urination.

Side effects other than those listed here may also occur. Talk to your doctor about any side effect that seems unusual or that is especially bothersome. You may report side effects to FDA at 1-800-FDA-1088.

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Dantrolene may increase the effects of other drugs that cause drowsiness, including antidepressants, alcohol, antihistamines, sedatives (used to treat insomnia), pain relievers, anxiety medicines, and other muscle relaxants. Tell your doctor about all medicines that you are taking, and do not take any medicine unless your doctor approves.

Drugs other than those listed here may also interact with dantrolene. Talk to your doctor and pharmacist before taking any prescription or over-the-counter medicines.

Other Names

Dantrium, Dantrium Intravenous, and dantrolene

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Every effort has been made to ensure that the information provided by Cerner Multum, Inc. ('Multum') is accurate, up-to-date, and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. Multum information has been compiled for use by healthcare practitioners and consumers in the United States and therefore Multum does not warrant that uses outside of the United States are appropriate, unless specifically indicated otherwise. Multum's drug information does not endorse drugs, diagnose patients or recommend therapy. Multum's drug information is an informational resource designed to assist licensed healthcare practitioners in caring for their patients and/or to serve consumers viewing this service as a supplement to, and not a substitute for, the expertise, skill, knowledge and judgment of healthcare practitioners. The absence of a warning for a given drug or drug combination in no way should be construed to indicate that the drug or drug combination is safe, effective or appropriate for any given patient. Multum does not assume any responsibility for any aspect of healthcare administered with the aid of information Multum provides. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the drugs you are taking, check with your doctor, nurse or pharmacist.

Copyright 1996-2004 Cerner Multum, Inc. Version 2.05. Revision date 8/23/04

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