Skip to main content

Dantrium Side Effects

Generic name: dantrolene

Medically reviewed by Last updated on Feb 8, 2024.

Note: This document contains side effect information about dantrolene. Some dosage forms listed on this page may not apply to the brand name Dantrium.

Applies to dantrolene: oral capsule. Other dosage forms:


Oral route (Capsule)

Dantrolene may cause hepatotoxicity, and symptomatic hepatitis (fatal and nonfatal) has been reported at various dose levels. Risk of hepatic injury appears to be greater in patients taking a higher dosage, in females, in patients older than 35 years, and in patients taking additional medication(s). Monitor hepatic function, including frequent determination of SGOT or SGPT, during therapy. Discontinue therapy after 45 days if there is no observable benefit.

Serious side effects of Dantrium

Along with its needed effects, dantrolene (the active ingredient contained in Dantrium) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention. Serious side effects are very rare when dantrolene is taken for a short time, for example, when it is used for a few days before, during, or after surgery or anesthesia to prevent or treat malignant hyperthermia. However, serious side effects may occur, especially when the medicine is taken for a long time.

Check with your doctor immediately if any of the following side effects occur while taking dantrolene:

Less common

Other side effects of Dantrium

Some side effects of dantrolene may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

For Healthcare Professionals

Applies to dantrolene: intravenous powder for injection, oral capsule.


The more commonly reported adverse reactions have included loss of grip strength, leg weakness, drowsiness, dizziness, nausea, fatigue, diarrhea, thrombophlebitis, and injection site reactions.[Ref]


Common (1% to 10%): Hepatotoxicity, liver function test abnormalities

Frequency not reported: Jaundice, hepatitis, hepatic dysfunction including fatal hepatic failure[Ref]


Common (1% to 10%): Dysphagia, nausea, vomiting, abdominal pain

Uncommon (0.1% to 1%): Constipation

Rare (less than 0.1%): Intestinal obstruction

Frequency not reported: Abdominal cramps, anorexia, alteration of taste, gastrointestinal bleeding, gastric irritation, diarrhea[Ref]

Several reports of severe constipation and abdominal distention leading to functional obstruction have been reported. Diarrhea may be severe and may necessitate temporary withdrawal of therapy. If diarrhea recurs, therapy should probably be permanently discontinued.[Ref]


Postmarketing reports: Anaphylaxis


Common (1% to 10%): Infusion site pain

Postmarketing reports: Thrombophlebitis and tissue necrosis[Ref]


Frequency not reported: Abnormal hair growth, acne-like rash, eczematoid eruption, sweating, urticaria, rash, erythema[Ref]

Nervous system

Very common (10% or more): Somnolence (up to 17%), dysphonia (13%)

Common (1% to 10%): Headache, dizziness, seizure, lightheadedness, drooling[Ref]


Frequency not reported: Mental depression, mental confusion, insomnia, nervousness


Frequency not reported: Incontinence, increased urinary frequency, urinary retention, hematuria, crystalluria, nocturia, difficult urination and/or urinary retention, difficult erection


Very common (10% or more): Flushing

Common (1% to 10%): Pericarditis, atrioventricular block, tachycardia

Uncommon (0.1% to 1%): Exacerbation of preexisting cardiac insufficiency

Frequency not reported: Bradycardia, labile blood pressure, erratic blood pressure, heart failure, phlebitis[Ref]


Common (1% to 10%): Pleural effusion with associated eosinophilia

Rare (0.01% to 0.1%): -or- Rare (less than 0.1%):

Frequency not reported: Feeling of suffocation, respiratory depression, respiratory failure, dyspnea

Postmarketing reports: Pulmonary edema[Ref]

Pulmonary edema has developed during treatment of malignant hyperthermia; the contributory effect of the diluent volume and mannitol in these cases is not known.[Ref]


Common (1% to 10%): Muscular weakness, extremity pain

Frequency not reported: Myalgia, backache[Ref]


Frequency not reported: Aplastic anemia, leukopenia, lymphocytic lymphoma, thrombocytopenia[Ref]


Common (1% to 10%): Blurred vision

Frequency not reported: Visual disturbances, diplopia, excessive tearing[Ref]


Common (1% to 10%): Feeling abnormal

Frequency not reported: Chills, fever, general malaise[Ref]


Frequency not reported: Transient lowering of GFR and renal plasma flow following 8 weeks of oral therapy


1. Cerner Multum, Inc. "UK Summary of Product Characteristics."

2. Cerner Multum, Inc. "Australian Product Information."

3. Utili R, Boitnott JK, Zimmerman HJ (1977) "Dantrolene-associated hepatic injury. Incidence and character." Gastroenterology, 72, p. 610-6

4. Wilkinson SP, Portmann B, Williams R (1979) "Hepatitis from dantrolene sodium." Gut, 20, p. 33-6

5. Chan CH (1990) "Dantrolene sodium and hepatic injury." Neurology, 40, p. 1427-32

6. (2001) "Product Information. Dantrium (dantrolene)." Procter and Gamble Pharmaceuticals

7. Dykes MH (1975) "Evaluation of a muscle relaxant: dantrolene sodium (Dantrium)." JAMA, 231, p. 862-4

8. Shaivitz SA (1974) "Letter: Dantrolene." JAMA, 229, p. 1282-3

9. Pembroke AC, Saxena SR, Kataria M, Zilkha KD (1981) "Acne induced by dantrolene." Br J Dermatol, 104, p. 465-8

10. Allen GC, Cattran CB, Peterson RG, Lalande M (1988) "Plasma levels of dantrolene following oral administration in malignant hyperthermia-susceptible patients." Anesthesiology, 69, p. 900-4

11. Chyatte SB, Basmajian JV (1973) "Dantrolene sodium: long-term effects in severe spasticity." Arch Phys Med Rehabil, 54, p. 311-5

12. Andrews LG, Muzumdar AS, Pinkerton AC (1975) "Letter: Hallucinations associated with dantrolene sodium therapy." Can Med Assoc J, 112, p. 148

13. Petusevsky ML, Faling LJ, Rocklin RE, Snider GL, Merliss AD, Moses JM, Dorman SA (1979) "Pleuropericardial reaction to treatment with dantrolene." JAMA, 242, p. 2772-4

14. Miller DH, Haas LF (1984) "Pneumonitis with dantrolene." J Neurol Neurosurg Psychiatry, 47, p. 553-4

15. Felz MW, HavilandFoley DJ (2001) "Eosinophilic pleural effusion due to dantrolene: Resolution with steroid therapy." South Med J, 94, p. 502-4

16. Pace-Balzan A, Ramsden RT (1988) "Sudden bilateral sensorineural hearing loss during treatment with dantrolene sodium (dantrium)." J Laryngol Otol, 102, p. 57-8

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.