Ryanodex (injection)

Generic name: dantrolene (injection) [ DAN-troe-leen ]
Other brand names of dantrolene (injection) include: Dantrium Intravenous, Revonto, Ryanodex
Drug class: Skeletal muscle relaxants

Medically reviewed by Drugs.com on Jun 30, 2025. Written by Cerner Multum.

What is Ryanodex?

Ryanodex is used to treat or prevent muscle stiffness or twitching caused by malignant hyperthermia (a rapid increase in body temperature and severe muscle contractions) that can occur during surgery with certain types of anesthesia.

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

Ryanodex 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.

Tell your medical caregivers right away if you have:

• loss of grip strength, loss of balance and weakness in the legs;

• shortness of breath;

• trouble swallowing;

• dizziness, extreme drowsiness, falling asleep suddenly, even after feeling alert; or

• pain, burning, warmth, redness, bruising, irritation, or skin changes where the injection was given.

Common side effects of Ryanodex may include:

• nausea;

• skin redness; or

• pain, bruising, swelling, or irritation where the medicine was injected.

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

Warnings

Use only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies.

Before taking this medicine

Tell your doctor if you have or ever had health problems or use other medications.

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

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

How is Ryanodex given?

Ryanodex is injected into a vein by a healthcare provider in a medical setting.

Tell your medical caregivers if you feel any burning or pain when Ryanodex is injected.

What happens if I miss a dose?

In a medical setting you are not likely to miss a dose.

What happens if I overdose?

In a medical setting an overdose would be treated quickly.

What should I avoid after receiving Ryanodex?

Avoid driving or hazardous activity until you know how Ryanodex will affect you. Your reactions could be impaired. Ryanodex may cause a light-headed feeling that may last up to 48 hours.

This medication can cause muscle weakness (especially in your hands and legs) and trouble swallowing. Use caution with daily activities to avoid injury before your muscle strength has returned completely.

What other drugs will affect Ryanodex?

Using Ryanodex with other drugs that make you drowsy can worsen this effect. 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:

• a heart or blood pressure medication called a calcium channel blocker; or

• vecuronium (muscle relaxer used during medical procedures).

This list is not complete. Other drugs may affect Ryanodex, 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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