Dantrolene (Oral)

Dantrolene is also known under US brand name Dantrium and is a drug taken orally to treat muscle spasticity issues that are caused by a variety of conditions.


Dantrolene is used to help relax some muscles in your body. It relieves the cramping, spasms, and tightness of muscles caused by certain medical problems such as cerebral palsy, multiple sclerosis (MS), injury to the spine or stroke. Dantrolene doesn't cure these problems, but it can allow other treatments, such as physical therapy, to prove more helpful in aiding the condition. Dantrolene produces relaxant effects by acting directly on the muscles.

This drug is also used to prevent or treat a medical problem that's known as malignant hyperthermia. This can occur in some patients during or following anesthesia or surgery. Malignant hyperthermia consists of a group of symptoms including fast and irregular heartbeat, very high fever and breathing problems. It is believed that the tendency to develop this medical condition is inherited. This medication is only available via prescription from your doctor and is available in the dosage form: capsule.

Condition(s) treated?

  • Muscle Spasm
  • Muscle Spasms due to a Brain Disease
  • Muscle Spasms caused by a Spinal Disease
  • Malignant Hyperthermia
  • Neuroleptic Malignant Syndrome
  • Treatment to Prevent Malignant Hyperthermia
  • Muscle Pain from Deficiency of the Enzyme Phosphorylase

Type of medicine?

  • Capsule

Side Effects

Along with its intended effects, the consumption of dantrolene can produce some unwanted side effects. Whilst all these side effects may not appear at once, if they do appear, they may require medical attention.

Inform your doctor or a healthcare professional immediately if you suffer from any of the following side effects whilst taking dantrolene:

Less common side effects

  • Bloody or black, tarry stools
  • Bluish color changes in skin color
  • Bloody or dark urine
  • Changes in speech
  • Constipation
  • Chest pain
  • Confusion
  • Convulsions (seizures)
  • Decrease in urine volume
  • Decrease in frequency of urination
  • Difficult urination
  • Difficulty in passing urine (dribbling)
  • Difficulty in moving
  • Difficulty in swallowing
  • Increased frequency of urination
  • Pounding, fast, or irregular heartbeat or pulse
  • Increased urge to urinate during the night
  • Light-colored stools
  • Joint pain
  • Lightheadedness
  • Mental depression
  • Loss of bladder control
  • Muscle cramping or aching
  • Pain in the lower back
  • Muscle stiffness or pains
  • Muscle spasm or jerking of all extremities
  • Vomiting or nausea
  • Pain or burning while urinating
  • Painful urination
  • Tenderness, pain or changes in skin color
  • Severe stomach pain
  • Troubled or slow breathing
  • Shortness of breath
  • Skin rash, hives, or itching
  • Sudden decrease in amount of urine
  • Swelling of foot or leg
  • Sudden loss of consciousness
  • Swollen joints
  • Upper right abdominal pain
  • Unusual weakness or tiredness
  • Vomiting of blood or material that looks like coffee grounds
  • Yellow skin or eyes
  • Waking to urinate at night

Some side effects of dantrolene that occur do not usually require medical attention. You will usually find that these side effects begin to disappear once your body begins to adjust to the medication. If these side effects are annoying you, you should contact your doctor or local pharmacist for advice on how to prevent or reduce these side effects.

More common side effects

  • Dizziness
  • Diarrhea
  • Drowsiness
  • Muscle weakness
  • General feeling of illness or discomfort

Less common side effects

  • Abdominal or stomach cramps or discomfort
  • Acne-like rash
  • Abnormal hair growth
  • Double or blurred vision or any change in vision
  • Fever or chills
  • Change in taste
  • Disturbed color perception
  • Halos around lights
  • Excessive tearing
  • Headache
  • Itching skin
  • Night blindness
  • Loss of appetite
  • Overbright appearance of lights
  • Seeing double
  • Redness of skin
  • Skin rash, encrusted, scaly and oozing
  • Slurring of speech or other speech problems
  • Sleeplessness
  • Sudden decrease in amount of urine
  • Tunnel vision
  • Unable to sleep
  • Sweating
  • Trouble in sleeping
  • Weight loss
  • Unusual nervousness

Remember you can report all side effects to the FDA on 1-800-FDA-1088.


The final dosage of any medication will depend on a number of factors. This includes your age, weight, and height, the current medications you are taking, what condition you are being treated for, the severity of the condition and how you react to the first dose. Do not stop, change or alter a dose without the guidance of your doctor.

Dantrolene can be taken with or without food or on an empty or full stomach. However, if your doctor tells you to take the medication a certain way, then do so as directed.

Take this medication only as directed by your doctor.

Typical Adult Dose for Malignant Hyperthermia

Oral: 4 - 8 mg/kg/day taken orally in 3 or 4 divided doses for one to two days prior to surgery. The last dose should be given with water approximately three to four hours before the scheduled surgery. Adjustments can usually be made within the recommended dosage range to avoid excessive gastrointestinal irritation (vomiting or nausea) or incapacitation (drowsiness, weakness etc.).

Typical Adult Dose for Chronic Spasticity

25 mg given once daily for seven days, then
25 mg three times daily for seven days, then
50 mg three times daily for seven days, then
100 mg three times daily.

Before administration, consideration should be given to the individual potential response to treatments. A decrease in spasticity should be sufficient enough to allow daily function. This should be the therapeutic goal of the treatment with this drug.

It's important to establish a therapeutic goal before beginning treatment with dantrolene.

Dosage should be individualized and titrated for maximum effect. The lowest dose compatible with the optimal response is recommended.

Some patients will not respond until a higher daily dosage is achieved. Each dosage level given should be maintained for 7 days to determine the response of the patient. If no benefit is observed at the next high dose, then it should be decreased to the previous lower dose that was maintainable.

Typical Pediatric Dose for Malignant Hyperthermia

Oral: 4 - 8 mg/kg/day taken orally in 3- 4 divided doses for one or two days prior to surgery, with the last dose being given with water approximately three to four hours before scheduled surgery. Adjustments can be made within the recommended dosage range to avoid excessive gastrointestinal irritation (vomiting or nausea), or incapacitation (drowsiness or weakness).

Typical Pediatric Dose for Chronic Spasticity

0.5 mg/kg once daily for seven days, then
0.5 mg/kg three times daily for seven days, then
1 mg/kg three times daily for seven days, then
2 mg/kg three times daily.

Doses should be individualized and titrated for maximum effect. The lowest dose that is compatible with the optimal response is recommended.

If you miss a dose of this medication, you should take it as soon as possible, unless it is almost time for your next dose. In this case, you should skip the missed dose and go back to the regular dosing schedule as established by your doctor or healthcare professional. Don't double dose.


Drug interactions can cause some severe side effects and affect the effectiveness of either drug. To limit these interactions, you should let your doctor know of all the medications you have taken in the past or are currently taking. This list should include all prescription and non-prescription drugs, your past medical history including any medical conditions you are currently suffering from, and any health conditions that run in your family.

The use of the medication is not usually recommended with the following drugs. However, in some cases, it may be required. If you are prescribed both medications together, your doctor may alter the dose or frequency in which you use one or both medications.

  • Alprazolam
  • Alfentanil
  • Amlodipine
  • Anileridine
  • Amobarbital
  • Aprobarbital
  • Butalbital
  • Buprenorphine
  • Butabarbital
  • Butorphanol
  • Chloral Hydrate
  • Carisoprodol
  • Chlordiazepoxide
  • Clevidipine
  • Chlorzoxazone
  • Cinnarizine
  • Clobazam
  • Clorazepate
  • Clonazepam
  • Codeine
  • Diazepam
  • Dantrolene
  • Dihydrocodeine
  • Estazolam
  • Diltiazem
  • Ethchlorvynol
  • Fentanyl
  • Felodipine
  • Flunitrazepam
  • Halazepam
  • Flurazepam
  • Hydrocodone
  • Isradipine
  • Hydromorphone
  • Levorphanol
  • Ketazolam
  • Lorazepam
  • Medazepam
  • Lormetazepam
  • Meperidine
  • Mephobarbital
  • Mephenesin
  • Meprobamate
  • Methadone
  • Metaxalone
  • Methocarbamol
  • Methotrexate
  • Methohexital
  • Midazolam
  • Morphine Sulfate Liposome
  • Morphine
  • Nicardipine
  • Nimodipine
  • Nifedipine
  • Nisoldipine
  • Oxazepam
  • Nitrazepam
  • Oxycodone
  • Pentazocine
  • Oxymorphone
  • Pentobarbital
  • Prazepam
  • Phenobarbital
  • Primidone
  • Quazepam
  • Propoxyphene
  • Remifentanil
  • Sodium Oxybate
  • Secobarbital
  • Sufentanil
  • Temazepam
  • Tapentadol
  • Thiopental
  • Triazolam
  • Verapamil
  • Tramadol

There are over 630 drugs that can interact with dantrolene. Some of these are listed below. You should let your doctor know if you are taking any of the following drugs and medications. This list is not complete.

  • Azatadine
  • Belladonna / butabarbital
  • Bedaquiline
  • Benztropine
  • Botulinum toxin type b
  • Biperiden
  • Black cohosh
  • Brentuximab
  • Brimonidine ophthalmic
  • Brexpiprazole
  • Brimonidine topical
  • Carbamazepine
  • Cannabis
  • Carbetapentane
  • Butabarbital
  • Buspirone
  • Chloral hydrate
  • Chlordiazepoxide / methscopolamine
  • Chlordiazepoxide
  • Chlordiazepoxide / clidinium
  • Chlormezanone
  • Clobazam
  • Chlorpheniramine
  • Clofarabine
  • Clonazepam
  • Clomipramine
  • Clorazepate
  • Cyclizine
  • Clozapine
  • Diazepam
  • Cyproheptadine
  • Diltiazem
  • Doxepin topical
  • Doxylamine
  • Divalproex sodium
  • Doxepin
  • Estazolam
  • Eslicarbazepine
  • Eszopiclone
  • Ethosuximide
  • Ethanol
  • Ethotoin
  • Felbamate
  • Ezogabine
  • Flavoxate
  • Fluoxetine / olanzapine
  • Flibanserin
  • Fluoxetine
  • Fluphenazine
  • Flurazepam
  • Fosphenytoin
  • Lazepam
  • Fluvoxamine
  • Haloperidol
  • Hydroxyzine
  • Heroin
  • Hyoscyamine / phenobarbital
  • Ifosfamide / mesna
  • Hyoscyamine / phenyltoloxamine
  • Idelalisib / ifosfamide
  • Iloperidone
  • IncobotulinumtoxinA
  • Imipramine
  • Interferon beta-1a
  • Isocarboxazid
  • Interferon beta-1b
  • Kava
  • Lamotrigine
  • Ketamine
  • Evetiracetam
  • Lithium
  • Levocetirizine
  • Lorazepam
  • Lurasidone
  • Loxapine
  • Magnesium salicylate / phenyltoloxamine
  • Mephenytoin
  • Maprotiline
  • Mephobarbital
  • Mesoridazine
  • Meprobamate
  • Metaxalone
  • Metoclopramide
  • Methotrexate
  • Methsuximide
  • Metyrosine
  • Mirtazapine
  • Midazolam
  • Molindone
  • Naltrexone
  • Nabilone
  • Nefazodone
  • Olanzapine
  • Nortriptyline
  • Olopatadine nasal
  • Opium
  • OnabotulinumtoxinA
  • Oxazepam
  • Paliperidone
  • Oxcarbazepine
  • Paraldehyde
  • Paroxetine
  • Paramethadione
  • Peginterferon beta-1a
  • Perampanel
  • Pentobarbital
  • Pergolide
  • Phenytoin
  • Perphenazine
  • Phenacemide
  • Pimozide
  • Pregabalin
  • Pramipexole
  • Primidone
  • Procyclidine
  • Prochlorperazine
  • Promazine
  • Propiomazine
  • Promethazine
  • Protriptyline
  • Quetiapine
  • Quazepam
  • Ramelteon
  • Risperidone
  • Rasagiline
  • Ropinirole
  • Secobarbital
  • Rotigotine
  • Rufinamide
  • Sertraline
  • St. john's wort
  • Sibutramine
  • Suvorexanttasimelteon
  • Tetrabenazine
  • Temazepam
  • Thalidomide
  • Tiagabine
  • Thioguanine
  • Thioridazine
  • Thiothixene
  • Tizanidine
  • Trabectedin
  • Tolcapone
  • Topiramate
  • Trandolapril / verapamil
  • Trazodone
  • Tranylcypromine
  • Triazolam
  • Triflupromazine
  • Trifluoperazine
  • Trihexyphenidyl
  • Trimethadione
  • Trimeprazine
  • Trimipramine
  • Trimethobenzamide
  • Tripelennamine
  • Valbenazine
  • Triprolidine
  • Valerian
  • Venlafaxine
  • Valproic acid
  • Vecuronium
  • Verapamil
  • Zaleplon
  • Vigabatrin
  • Ziconotide
  • Zolpidem
  • Ziprasidone
  • Zonisamide

Other medical problems

If you suffer from any other medical problems, this may affect the use of this medication. Ensure you let your doctor know if you suffer from any other medical conditions, especially:

  • Liver disease, history of
  • Heart disease
  • Lung disease (e.g. asthma, emphysema, bronchitis)¬†- This drug may increase the risk of serious side effects.
  • Muscle spasms caused by rheumatic disorders¬†- This drug should not be used in patients who suffer from this condition.
  • Liver disease, active (e.g. cirrhosis, hepatitis)


Use in pediatric population

Studies have not been conducted on the relationship between age and the effects of dantrolene in children younger than five years of age. Therefore, efficacy and safety have not been established. This medication should not be given to children younger than five years old.

Use in geriatric population

No information is available from studies on the relationship of age to the effects of dantrolene in older patients.

Use in pregnancy and breastfeeding

This drug is under FDA pregnancy category C. It's unknown whether this medication will harm an unborn infant. Inform your doctor if you are pregnant or plan on becoming pregnant whilst using dantrolene.

With regards to breastfeeding, this drug can pass into breast milk and can cause potential harm to a nursing baby. You should not breastfeed a baby while using this medication.

The use of this drug can make you drowsy or dizzy. Don't use machinery, drive or do any activity that requires you to be alert. Be sure that you can perform these activities safely and limit your intake of alcoholic drinks.

This drug can make you more sensitive to the sun. Try to limit the time you spend in the sunshine. Avoid sunlamps and tanning booths. Wear protective clothing and use sunscreen when outdoors. Inform your doctor immediately if you have skin redness or blisters or if you sunburn.

Before taking this drug, let your pharmacist or doctor know if you are allergic to it, or if you suffer from any other allergies. This product can contain inactive ingredients, which could cause an allergic reaction or other issues. Speak with your pharmacist for more information.

This medication will add to the effects of other CNS depressants (medicines that slow down the nervous system, which could cause drowsiness). Some examples of CNS depressants are antihistamines, other allergies, or colds, tranquilizers, sedatives or sleeping medicine, muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before you take any of the medications listed above, while you are using this drug.


This medication should be stored in a closed container at room temperature, away from moisture, heat and direct light. Make sure you keep this drug from freezing. Keep this drug out of the reach of children.

Do not keep medicine that is no longer needed or is out of date.

Ask your doctor or healthcare professional for advice on how to correctly and safely dispose of this medication.


When used correctly, dantrolene is successful in the relaxing of certain muscles in your body. Due to a large number of interactions associated with this drug, it's important that you inform your doctor of all the current and past medications you are taking. This drug is not recommended for children under five years old. This drug should not be used while breastfeeding and let your doctor know if you are pregnant or intend to become pregnant whilst taking this medication. While using dantrolene, you may need regular blood tests to check the function of your liver. If you have any concerns or queries whilst taking this medication, consult your doctor or healthcare professional.