Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
Quick facts
- How it is given
- oral
- Type
- human prescription drug
- RxNorm ID
- 856652
We do not publish dosing. How much of this medicine to take, how often, and for how long depends on your age, weight, kidney and liver function, other conditions and other medicines. That is a decision for the person who prescribes or dispenses it. Follow the directions on your own pack and ask your pharmacist if anything is unclear.
What it is used to treat
INDICATIONS AND USAGE In Chronic Spasticity: Dantrolene sodium is indicated in controlling the manifestations of clinical spasticity resulting from upper motor neuron disorders (e.g., spinal cord injury, stroke, cerebral palsy, or multiple sclerosis). It is of particular benefit to the patient whose functional rehabilitation has been retarded by the sequelae of spasticity. Such patients must have presumably reversible spasticity where relief of spasticity will aid in restoring residual function. Dantrolene sodium is not indicated in the treatment of skeletal muscle spasm resulting from rheumatic disorders. If improvement occurs, it will ordinarily occur within the dosage titration (see DOSAGE AND ADMINISTRATION ), and will be manifested by a decrease in the severity of spasticity and the ability to resume a daily function not quite attainable without dantrolene sodium. Occasionally, subtle but meaningful improvement in spasticity may occur with dantrolene sodium therapy. In such instances, information regarding improvement should be solicited from the patient and those who are in constant daily contact and attendance with him. Brief withdrawal of dantrolene sodium for a period of 2 to 4 days will frequently demonstrate exacerbation of the manifestations of spasticity and may serve to confirm a clinical impression. A decision to continue the administration of dantrolene sodium on a long-term basis is justified if introduction of the drug into the patient's regimen: produces a significant reduction in painful and/or disabling spasticity such as clonus, or permits a significant reduction in the intensity and/or degree of nursing care required, or rids the patient of any annoying manifestation of spasticity considered important by the patient himself. In Malignant Hyperthermia: Oral dantrolene sodium is also indicated preoperatively to prevent or attenuate the development of signs of malignant hyperthermia in known, or strongly suspect, malignant hyperthermia susceptible patients who require anesthesia and/or surgery. […]
About this medicine
DESCRIPTION The chemical formula of dantrolene sodium is hydrated 1-[[[5-(4-nitrophenyl)-2-furanyl]methylene]amino]-2, 4-imidazolidinedione sodium salt. It is an orange powder, slightly soluble in water, but due to its slightly acidic nature the solubility increases somewhat in alkaline solution. The anhydrous salt has a molecular weight of 336. The hydrated salt contains approximately 15% water (3-1/2 moles) and has a molecular weight of 399. The structural formula for the hydrated salt is: Dantrolene sodium is supplied in capsules of 25 mg, 50 mg, and 100 mg. Inactive Ingredients: Each capsule contains Edible black ink, FD&C Yellow No. 6, Gelatin, Lactose, Magnesium stearate, Starch, Synthetic iron oxide red, Synthetic iron oxide yellow, Talc, and Titanium dioxide. Chemical Structure
Who should not take it
CONTRAINDICATIONS Active hepatic disease, such as hepatitis and cirrhosis, is a contraindication for use of dantrolene sodium . Dantrolene sodium is contraindicated where spasticity is utilized to sustain upright posture and balance in locomotion or whenever spasticity is utilized to obtain or maintain increased function.
Warnings
WARNINGS It is important to recognize that fatal and non-fatal liver disorders of an idiosyncratic or hypersensitivity type may occur with dantrolene sodium therapy. At the start of dantrolene sodium therapy, it is desirable to do liver function studies (SGOT, SGPT, alkaline phosphatase, total bilirubin) for a baseline or to establish whether there is pre-existing liver disease. If baseline liver abnormalities exist and are confirmed, there is a clear possibility that the potential for dantrolene sodium hepatotoxicity could be enhanced, although such a possibility has not yet been established. Liver function studies (e.g., SGOT or SGPT) should be performed at appropriate intervals during dantrolene sodium therapy. If such studies reveal abnormal values, therapy should generally be discontinued. Only where benefits of the drug have been of major importance to the patient, should reinitiation or continuation of therapy be considered. Some patients have revealed a return to normal laboratory values in the face of continued therapy while others have not. If symptoms compatible with hepatitis, accompanied by abnormalities in liver function tests or jaundice appear, dantrolene sodium should be discontinued. If caused by dantrolene sodium and detected early, the abnormalities in liver function characteristically have reverted to normal when the drug was discontinued. Dantrolene sodium therapy has been reinstituted in a few patients who have developed clinical and/or laboratory evidence of hepatocellular injury. If such reinstitution of therapy is done, it should be attempted only in patients who clearly need dantrolene sodium and only after previous symptoms and laboratory abnormalities have cleared. The patient should be hospitalized and the drug should be restarted in very small and gradually increasing doses. Laboratory monitoring should be frequent and the drug should be withdrawn immediately if there is any indication of recurrent liver involvement. Some patients have reacted with unmistakable signs of liver abnormality upon administration of a challenge dose, while others have not. […]
Reported side effects
ADVERSE REACTIONS The most frequently occurring side effects of dantrolene sodium have been drowsiness, dizziness, weakness, general malaise, fatigue, and diarrhea. These are generally transient, occurring early in treatment, and can often be obviated by beginning with a low dose and increasing dosage gradually until an optimal regimen is established. Diarrhea may be severe and may necessitate temporary withdrawal of dantrolene sodium therapy. If diarrhea recurs upon readministration of dantrolene sodium , therapy should probably be withdrawn permanently. Other less frequent side effects, listed according to system, are: Gastrointestinal: Constipation, rarely progressing to signs of intestinal obstruction, GI bleeding, anorexia, swallowing difficulty, gastric irritation, abdominal cramps, nausea and/or vomiting. Hepatobiliary: Hepatitis (see WARNINGS ). Neurologic: Speech disturbance, seizure, headache, light-headedness, visual disturbance, diplopia, alteration of taste, insomnia, drooling. Cardiovascular: Tachycardia, erratic blood pressure, phlebitis, heart failure. Hematologic: Aplastic anemia, anemia, leukopenia, lymphocytic lymphoma, thrombocytopenia. Psychiatric: Mental depression, mental confusion, increased nervousness. Urogenital: Increased urinary frequency, crystalluria, hematuria, difficult erection, urinary incontinence and/or nocturia, difficult urination and/or urinary retention. Integumentary: Abnormal hair growth, acne-like rash, pruritus, urticaria, eczematoid eruption, sweating. Musculoskeletal: Myalgia, backache. Respiratory: Feeling of suffocation, respiratory depression. Special Senses: Excessive tearing. Hypersensitivity: Pleural effusion with pericarditis, pleural effusion with associated eosinophilia, anaphylaxis. Other: Chills and fever. The published literature has included some reports of dantrolene sodium use in patients with Neuroleptic Malignant Syndrome (NMS). Dantrolene sodium capsules are not indicated for the treatment of NMS and patients may expire despite treatment with dantrolene sodium capsules. For medical advice about adverse reactions contact your medical professional. […]
Interactions with other medicines
Drug Interactions: Drowsiness may occur with dantrolene sodium therapy, and the concomitant administration of CNS depressants such as sedatives and tranquilizing agents may result in further drowsiness. While a definite drug interaction with estrogen therapy has not yet been established, caution should be observed if the two drugs are to be given concomitantly. Hepatotoxicity has occurred more often in women over 35 years of age receiving concomitant estrogen therapy. Cardiovascular collapse in patients treated simultaneously with verapamil and Dantrolene Sodium is rare. The combination of therapeutic doses of intravenous Dantrolene Sodium and verapamil in halothane/ α -chloralose anesthetized swine has resulted in ventricular fibrillation and cardiovascular collapse in association with marked hyperkalemia. Until the relevance of these findings to humans is established, the combination of Dantrolene Sodium and calcium channel blockers is not recommended during the management of malignant hyperthermia. Administration of dantrolene sodium may potentiate vecuronium-induced neuromuscular block.
If too much is taken
OVERDOSAGE Symptoms which may occur in case of overdose include, but are not limited to, muscular weakness and alterations in the state of consciousness (e.g., lethargy, coma), vomiting, diarrhea, and crystalluria. For acute overdose, general supportive measures should be employed along with immediate gastric lavage. Intravenous fluids should be administered in fairly large quantities to avert the possibility of crystalluria. An adequate airway should be maintained and artificial resuscitation equipment should be at hand. Electrocardiographic monitoring should be instituted, and the patient carefully observed. To date, no experience has been reported with dialysis and its value in dantrolene sodium overdose is not known.
Storing it safely
Store between 20° to 25°C (68° to 77°F) [See USP Controlled Room Temperature].
Before you take anything new
Tell your pharmacist or doctor about every medicine you take — including ones bought without a prescription, herbal products and supplements. Interactions are one of the most common avoidable causes of harm from medicines, and a pharmacist can check your full list in a couple of minutes.
This page is built from the openFDA record of the U.S. Food and Drug Administration's approved labelling for this product, effective 22 December 2024. Label text has been shortened and reformatted for readability; safety wording has not been altered in meaning. FDA labelling describes products approved in the United States — brand names, strengths, formulations and approved uses may differ in your country. Always read the leaflet that comes with your own pack. PocketsInfo is not affiliated with, and is not endorsed by, the FDA. Retrieved 2026-07-30.