Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Cancer: Dantrolene has been shown to cause cancer in rats. The potential for dantrolene to cause cancer in humans cannot be ruled out. If you have any questions or concerns, talk to your doctor.
Drowsiness/reduced alertness: This medication may temporarily cause drowsiness, which may impair your ability to drive or operate machinery. These effects should only last about a week. Avoid hazardous tasks for the first week of treatment.
Heart function: While taking this medication, people with heart disease should be closely monitored by their doctors.
Liver injury: Dantrolene capsules may be toxic to the liver, or worsen existing liver damage. The risk of liver injury is greater for women, people over 30 years of age, people taking other medications, and people taking other therapies that may cause liver damage. If you have liver disease, talk to your doctor about whether you should use this medication. People using this medication will likely have liver tests before and during use.
Lung function: While taking this medication, people with impaired lung function should be closely monitored by their doctors.
Muscle weakness: Some people taking dantrolene feel excessively weak as long as they are taking the medication. These people may not be able to use rehabilitation devices such as crutches, wheelchairs, braces, walkers, or canes. If you use any of these devices and experience persistent weakness that interferes with the use of these devices, you should talk to your doctor. You may have to stop taking this medication.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: This medication passes into breast milk. This medication should not be used by women who are breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children under 5 years of age.