Generic name: dantrolene (oral) [ DAN-troe-leen ]
Brand names: Dantrium, Revonto, Ryanodex, Dantrium Intravenous
Dosage forms: intravenous powder for injection (20 mg; 250 mg), oral capsule (100 mg; 25 mg; 50 mg)
Drug class: Skeletal muscle relaxants

Medically reviewed by Drugs.com on May 1, 2023. Written by Cerner Multum.

What is dantrolene?

Dantrolene is a muscle relaxer that 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 treat or prevent muscle stiffness and spasms caused by malignant hyperthermia (a rapid rise in body temperature and severe muscle contractions) that can occur during surgery with certain types of anesthesia.

Dantrolene may also be used for purposes not listed in this medication guide.

Dantrolene side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Call your doctor right away if you have signs of liver problems--nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes). These side effects may be most likely to occur between 3 and 12 months of your treatment with dantrolene.

Also call your doctor right away if you have:

• severe drowsiness;

• severe muscle weakness;

• weak or shallow breathing;

• severe or ongoing vomiting or diarrhea;

• problems with vision or speech;

• painful or difficult urination;

• a seizure; or

• a light-headed feeling, like you might pass out.

Common side effects of dantrolene may include:

• dizziness, drowsiness;

• diarrhea;

• weakness; or

• feeling tired.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Related/similar drugs

baclofen, Botox, Lioresal, onabotulinumtoxinA, Dantrium, Gablofen, Ryanodex

Warnings

You should not take dantrolene if you have active liver disease. Do not take dantrolene at a time when you need muscle tone for safe balance and movement during certain activities.

Dantrolene can cause life-threatening liver damage, especially if you take high doses. Do not take dantrolene in larger amounts or for longer than recommended.

Call your doctor right away if you have signs of liver problems such as nausea, upper stomach pain, loss of appetite, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

Before taking this medicine

You should not use dantrolene if you are allergic to it, or if you have:

• active liver disease such as hepatitis or cirrhosis.

Do not take dantrolene at a time when you need muscle tone for safe balance and movement during certain activities. In some situations, it may be dangerous for you to have reduced muscle tone.

You may be more likely to develop liver problems while using dantrolene if you are a woman, if you are older than 35, or if you also take other medications. Ask your doctor about your individual risk.

Tell your doctor if you have ever had:

• liver disease;

• heart disease or a heart attack; or

• a breathing disorder such as COPD (chronic obstructive pulmonary disease).

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Do not breastfeed while using this medicine, and for at least 3 days after your last dose.

Dantrolene should not be given to a child younger than 5 years old.

How should I take dantrolene?

Your doctor will perform blood tests to make sure you do not have conditions that would prevent you from safely using dantrolene.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.

Dantrolene can cause life-threatening liver damage, especially if you take high doses or take the medicine long-term. Use the medicine exactly as directed.

If you take dantrolene within 3 or 4 hours before surgery, use only enough water needed to swallow the capsule. Tell your doctor if you have trouble swallowing dantrolene.

You may need frequent blood tests to check your liver function.

Call your doctor if your muscle symptoms do not improve, or if they get worse.

If you need surgery, tell the surgeon ahead of time that you are using dantrolene.

Store at room temperature away from moisture, heat, and light. Keep the bottle tightly closed when not in use.

What happens if I miss a dose?

Use the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Overdose symptoms may include severe muscle weakness, vomiting, diarrhea, or fainting.

What should I avoid while taking dantrolene?

Avoid driving or hazardous activity until you know how dantrolene will affect you. Dizziness or drowsiness can cause falls, accidents, or severe injuries.

Avoid exposure to sunlight or tanning beds. Dantrolene can make you sunburn more easily. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

What other drugs will affect dantrolene?

Using dantrolene with other drugs that make you sleepy or slow your breathing can cause dangerous side effects or death. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

• heart or blood pressure medication;

• hormone replacement therapy; or

• hormonal birth control (pills, injections, implants, skin patches, or vaginal rings).

This list is not complete. Other drugs may affect dantrolene, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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