Prescription medication · Direct-Acting Muscle Relaxant
dantrolene
Also sold as Dantrium. Dantrolene treats muscle stiffness and spasms from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis.
Data updated 2026-05-15
- 580
- FDA reportsRarely reported
- 2
- InteractionsFew interactions
- $0.92
- Generic price (NADAC)
What the data shows
dantrolene (Dantrium) is a prescription Direct-Acting Muscle Relaxant, among the least-reported drugs the FDA tracks (580 FDA reports), with 2 documented drug interactions.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
dantrolene (Dantrium) is a prescription Direct-Acting Muscle Relaxant. Dantrolene treats muscle stiffness and spasms from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis.
Dantrolene is a muscle relaxant. It helps to reduce muscle spasms and stiffness caused by certain conditions.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.92/unit
Generic Available
Yes (4 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Dantrolene treats muscle stiffness and spasms from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis.
Common side effects
Drowsiness, Dizziness, Weakness
Key warnings
Dantrolene can potentially damage your liver.
The sections below are summarized in plain English from dantrolene's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
Dantrolene works directly on your muscles to relax them. It reduces the amount of calcium released in muscle cells. This helps to decrease muscle contractions and spasms.
How to Take It
Take dantrolene as directed by your doctor. The usual starting dose for adults is 25 mg once a day. Your doctor may gradually increase the dose every 7 days up to 100 mg four times a day. Take the medicine with water.
This is a plain-language summary of dantrolene's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. It is not known if dantrolene will harm your unborn baby. Talk to your doctor about the risks and benefits of taking dantrolene while breastfeeding.
This is a plain-language summary of dantrolene's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of dantrolene's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store dantrolene capsules at room temperature, between 68° to 77°F.
Side Effects (from patient reports)
Based on 580 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for dantrolene, by number of reports
- A severe reaction to certain drugs that causes fever, muscle stiffness, and changes in mental status
A severe reaction to certain drugs that causes fever, muscle stiffness, and changes in mental status
81 reports
- Fever 30
Fever
30 reports
- The medicine is reacting with another medicine 27
The medicine is reacting with another medicine
27 reports
- Accidentally falling down 26
Accidentally falling down
26 reports
- Very high body temperature 26
Very high body temperature
26 reports
- Stiff muscles 25
Stiff muscles
25 reports
- Breakdown of muscle tissue 25
Breakdown of muscle tissue
25 reports
- The medicine is not working for a condition it is not approved for 24
The medicine is not working for a condition it is not approved for
24 reports
- Fast heart rate 23
Fast heart rate
23 reports
- Infection in the bladder or urinary system 23
Infection in the bladder or urinary system
23 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for dantrolene each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where dantrolene sits
dantrolene has more FDA adverse-event reports than 4% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is dantrolene; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 580 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
580
Reports Mentioning Death
71
12.2% of reports — not proof of cause
Hospitalization Reports
288
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 2 | NEUROLEPTIC MALIGNANT SYNDROME | 81 |
| 4 | PYREXIA | 30 |
| 5 | DRUG INTERACTION | 27 |
| 6 | FALL | 26 |
| 7 | HYPERTHERMIA | 26 |
| 8 | MUSCLE RIGIDITY | 25 |
| 9 | RHABDOMYOLYSIS | 25 |
| 10 | DRUG INEFFECTIVE FOR UNAPPROVED INDICATION | 24 |
| 11 | TACHYCARDIA | 23 |
| 12 | URINARY TRACT INFECTION | 23 |
| 13 | FATIGUE | 22 |
| 14 | HYPERTENSION | 21 |
| 15 | TREMOR | 21 |
| 16 | MUSCLE SPASMS | 20 |
| 17 | PAIN | 19 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Dantrolene can potentially damage your liver. Your doctor should monitor your liver function with blood tests. Tell your doctor if you have any signs of liver problems, such as yellowing of the skin or eyes, dark urine, or abdominal pain. If you don't see any benefit after 45 days, stop taking dantrolene.
Known Drug Interactions
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.
Mechanism: Combining these drugs may lead to very high potassium levels, which can cause the heart to stop working correctly.
What to do: Use this combination with extreme caution and talk to your doctor about the risks of heart problems.
Concomitant use of carbamazepine with olanzapine, dantrolene, or ibuprofen may increase plasma carbamazepine levels.
Mechanism: Dantrolene can slow down how your body processes carbamazepine, causing the drug to build up in your system.
What to do: Your doctor may need to check your blood levels and watch for side effects.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
Can I drive while taking dantrolene?
How long does it take for dantrolene to start working?
Can I take dantrolene with other medications?
What should I do if I experience severe diarrhea?
Is dantrolene a cure for spasticity?
Can I stop taking dantrolene suddenly?
Does dantrolene interact with alcohol?
What if I am over 65?
Can dantrolene cause me to fall?
Will dantrolene help with muscle spasms from arthritis?
What are the common side effects of dantrolene?
Does dantrolene interact with other medications?
What drug class is dantrolene?
Is dantrolene safe during pregnancy?
Related Medications in Direct-Acting Muscle Relaxant
Other drugs grouped near dantrolene - same-class peers and common alternatives.
baclofen
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Baclofen is a muscle relaxant.
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botulinum toxin A
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carisoprodol
Soma
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chlorzoxazone
Parafon Forte
Chlorzoxazone is a muscle relaxant.
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cyclobenzaprine
Flexeril, Amrix
Cyclobenzaprine is a muscle relaxant.
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What the FDA Data Shows for dantrolene
The FDA label for dantrolene (sold under brand names such as Dantrium) classifies it as a prescription-only medication in the Direct-Acting Muscle Relaxant class. Dantrolene treats muscle stiffness and spasms from conditions like spinal cord injury, stroke, cerebral palsy, or multiple sclerosis. Official labeling lists 6 commonly reported side effects, including Drowsiness, Dizziness, Weakness.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 580 voluntary reports. The database also lists 2 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.92.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 22, 2024
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages