Dantrolene (injection)

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

Dantrolene may also be used for reasons not mentioned in this medication guide.

Use only as directed. Inform your doctor if you are taking other medicines or have any other medical conditions or allergies.

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

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

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

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

Inform your medical caregivers immediately if you experience:

• loss of grip strength, loss of balance, and weakness in your legs;
• shortness of breath;
• trouble swallowing;
• dizziness, extreme drowsiness, or suddenly falling asleep, even when you feel alert; or
• pain, burning, warmth, redness, bruising, irritation, or changes in your skin where the injection was given.

Common side effects of dantrolene 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. Contact your doctor for medical advice about side effects. You can report side effects to FDA at 1-800-FDA-1088.

Dantrolene 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 dantrolene is injected.

In a medical setting, it is very unlikely that you will miss a dose.

In a medical setting, an overdose will be treated quickly.

Do not drive or engage in hazardous activities until you know how dantrolene will affect you. Your reactions could be impaired. Dantrolene may cause a light-headed feeling that could last up to 48 hours.

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

Using dantrolene with other drugs that make you sleepy can make this effect stronger. Talk to your doctor before taking 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 (a muscle relaxer used during medical procedures).

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