What Is Dantrolene? Uses, Dosage, and What You Need to Know in 2026

What Is Dantrolene?

Dantrolene is a prescription muscle relaxant that works directly on skeletal muscles to reduce spasticity — the abnormal tightness and stiffness caused by conditions affecting the brain and spinal cord.

Unlike most muscle relaxants that act on the central nervous system, Dantrolene is a direct-acting skeletal muscle relaxant. It works at the muscle level by blocking calcium release inside muscle cells, which reduces the force of muscle contractions. This unique mechanism makes it the only FDA-approved oral medication that works peripherally (at the muscle) rather than centrally (in the brain or spinal cord) to treat spasticity.

Brand Names and Forms

Dantrolene sodium is available under several brand names:

• Dantrium — The original brand name for both oral capsules and the injectable form
• Revonto — An injectable form used in hospitals for malignant hyperthermia
• Ryanodex — A concentrated injectable form that can be prepared more quickly in emergency situations

For most patients with spasticity, the oral capsule form (generic dantrolene sodium) is what you'll be prescribed. It's available in 25 mg, 50 mg, and 100 mg capsules.

Dantrolene was first approved by the FDA in 1974, so it has a long track record of use. The patent expired decades ago, and affordable generic versions are widely available.

What Is Dantrolene Used For?

Dantrolene has two primary FDA-approved uses:

1. Chronic Muscle Spasticity

Dantrolene is prescribed for spasticity caused by upper motor neuron disorders, including:

• Multiple sclerosis (MS) — Spasticity affects up to 80% of MS patients and can significantly impact mobility and quality of life
• Spinal cord injury — Damage to the spinal cord often results in chronic muscle tightness below the level of injury
• Stroke — Post-stroke spasticity can develop weeks to months after the event
• Cerebral palsy — Children and adults with cerebral palsy may experience spasticity that limits movement and causes pain

Dantrolene is typically considered when other muscle relaxants like Baclofen or Tizanidine haven't provided adequate relief, or when their central nervous system side effects (like heavy sedation) are problematic.

2. Malignant Hyperthermia

Dantrolene is the only FDA-approved treatment for malignant hyperthermia — a rare but life-threatening reaction to general anesthesia. During a malignant hyperthermia crisis, muscles contract uncontrollably, causing the body temperature to skyrocket. Intravenous Dantrolene is administered in the operating room to stop this reaction.

Dantrolene is also used to prevent malignant hyperthermia in patients known to be susceptible before they undergo surgery.

Off-Label Uses

Doctors sometimes prescribe Dantrolene off-label for:

• Neuroleptic malignant syndrome (NMS) — A dangerous reaction to antipsychotic medications that resembles malignant hyperthermia
• Drug-induced hyperthermia — Including overdoses of substances that cause dangerously high body temperatures

How Is Dantrolene Taken?

Starting Dose

For spasticity in adults, Dantrolene is started at a low dose and increased gradually:

• Week 1: 25 mg once daily
• Week 2: 25 mg three times daily
• Week 3: 50 mg three times daily
• Week 4 and beyond: Increase as needed, up to a maximum of 100 mg three to four times daily

The maximum daily dose is 400 mg. Your doctor will find the lowest dose that effectively manages your spasticity while minimizing side effects.

For Children (Age 5 and Older)

Dosing is weight-based:

• Start at 0.5 mg/kg once daily
• Gradually increase to 0.5 mg/kg three times daily, then 1 mg/kg three times daily, then 2 mg/kg three times daily
• Maximum: 100 mg four times daily

Important Tips

• Take Dantrolene with food or milk to reduce stomach upset
• Swallow capsules whole — do not crush or chew
• Take it at the same times each day for consistent levels in your body
• Do not stop Dantrolene suddenly without talking to your doctor
• If you miss a dose, take it as soon as you remember — but skip it if it's almost time for your next dose

Who Should Not Take Dantrolene?

Dantrolene is not appropriate for everyone. You should not take oral Dantrolene if you have:

• Active liver disease — Including hepatitis B or C, cirrhosis, or non-alcoholic fatty liver disease. Dantrolene carries a Black Box Warning for liver damage.
• A need for spasticity to maintain function — Some patients rely on a certain level of muscle tone to stand, walk, or maintain posture. Reducing spasticity too much could impair function.

Use caution if you:

• Are over 35 years old and female, especially if taking estrogen (higher liver damage risk)
• Take medications that interact with Dantrolene, including calcium channel blockers like Verapamil
• Have heart or lung disease
• Are pregnant or breastfeeding (Dantrolene is FDA pregnancy category C)

How Much Does Dantrolene Cost?

The cost of Dantrolene varies significantly depending on where you fill your prescription and whether you use insurance or a discount card:

• Retail price (without insurance): $88–$200 per month, depending on dose and pharmacy
• With a GoodRx or SingleCare coupon: As low as $22–$30 per month
• With insurance: Your copay will depend on your plan, but Dantrolene is typically covered as a generic tier 1 or tier 2 medication

For more detailed savings strategies, see our full guide: How to Save Money on Dantrolene.

If cost is a barrier, patient assistance programs from organizations like NeedyMeds and RxAssist may help you get Dantrolene for free or at a reduced cost.

What Are the Side Effects?

The most common side effects of Dantrolene include:

• Drowsiness and fatigue
• Dizziness
• Muscle weakness
• Diarrhea
• Nausea

The most serious risk is liver damage (hepatotoxicity), which carries an FDA Black Box Warning. Regular liver function tests are required while taking Dantrolene. For a complete breakdown, read our guide on Dantrolene side effects.

How Does Dantrolene Compare to Other Muscle Relaxants?

Here's how Dantrolene stacks up against the two most commonly prescribed alternatives:

• Baclofen (Lioresal): Acts on the spinal cord (centrally). More sedating but no liver warning. First-line for most spasticity. Costs $10–$25/month with coupons.
• Tizanidine (Zanaflex): Acts on the brain (centrally). Short-acting, good for intermittent spasticity. Also requires liver monitoring. Costs $10–$20/month with coupons.
• Dantrolene: Acts at the muscle (peripherally). Less sedating than Baclofen but carries the liver Black Box Warning. Costs $22–$30/month with coupons.

For a deeper comparison, see: How Does Dantrolene Work?

Final Thoughts

Dantrolene is a unique and effective medication for chronic spasticity and the only FDA-approved treatment for malignant hyperthermia. Its peripheral mechanism of action sets it apart from other muscle relaxants, offering an alternative for patients who can't tolerate the sedation of centrally-acting drugs.

If you've been prescribed Dantrolene, make sure you understand the importance of liver monitoring, know the side effects to watch for, and have a plan for finding it at a pharmacy.

Looking for Dantrolene near you? Use Medfinder to find a pharmacy with it in stock and compare prices.