Dantrolene

Dantrolene is used to treat muscle stiffness or twitching caused by conditions like a spinal cord injury, stroke, cerebral palsy, or multiple sclerosis.

Dantrolene is also 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 happen during surgery with certain types of anesthesia.

Dantrolene may also be used for other reasons that are not listed in this medication guide.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may change your dose from time to time. Use the medicine exactly as directed.

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

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

Call your doctor if your symptoms do not improve after 45 days, or if they get worse.

If you need surgery, inform the surgeon in advance that you are using dantrolene.

Store tightly closed at room temperature, away from moisture and heat.

Dantrolene may lead to serious liver damage, particularly if you take high doses. Do not take dantrolene in larger amounts or for a longer time than your doctor has prescribed.

Contact your doctor immediately if you notice signs of liver issues, including loss of appetite, nausea, vomiting, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, or jaundice (yellowing of the skin or eyes).

You should not use dantrolene if you are allergic to it, or if you have hepatitis, cirrhosis, or other liver disease.

You should also not take dantrolene at a time when you need muscle tone for safe balance and movement during certain activities. In some situations, having reduced muscle tone may be dangerous for you.

Tell your doctor if you have or have ever had:

• heart disease or a heart attack; or
• a breathing disorder such as chronic obstructive pulmonary disease (COPD).

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

Do not use dantrolene if you are breastfeeding.

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

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

Dantrolene may cause life-threatening liver damage, especially if you take high doses or use the medicine for a long time. Call your doctor right away if you have signs of liver problems: loss of appetite, nausea, vomiting, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Also call your doctor right away if you have:

• weak or shallow breathing;
• severe or ongoing diarrhea;
• problems with vision or speech;
• painful or difficult urination;
• seizure, a light-headed feeling, like you might pass out;
• trouble swallowing, loss of appetite;
• depression, confusion, nervousness;
• stomach bleeding--bloody or tarry stools, coughing up blood or vomit that looks like coffee grounds;
• heart problems--swelling, rapid weight gain, feeling short of breath, fast heart rate, irregular blood pressure; or
• low blood cell counts--fever, chills, tiredness, mouth sores, skin sores, easy bruising, unusual bleeding, pale skin, cold hands and feet, feeling light-headed or short of breath.

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.

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

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

Overdose symptoms may include severe tiredness, fainting, muscle weakness, vomiting, diarrhea, or problems with urination.

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

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.

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

Using dantrolene with other drugs that make you drowsy can increase this effect. Consult your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Inform your doctor about all your other medicines, especially:

• a heart or blood pressure medication called a calcium channel blocker;
• birth control pills and other hormones; or
• vecuronium (muscle relaxer used during medical procedures).

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.