Medically reviewed by Drugs.com. Last updated on Dec 15, 2021.
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 .
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Skeletal Muscle Relaxant, Direct Acting
Uses for dantrolene
Dantrolene is used to help relax certain muscles in your body. It relieves the spasms, cramping, and tightness of muscles caused by certain medical problems such as multiple sclerosis (MS), cerebral palsy, stroke, or injury to the spine. Dantrolene does not cure these problems, but it may allow other treatment, such as physical therapy, to be more helpful in improving your condition. Dantrolene acts directly on the muscles to produce its relaxant effects.
Dantrolene is also used to prevent or treat a medical problem called malignant hyperthermia that may occur in some patients during or following surgery or anesthesia. Malignant hyperthermia consists of a group of symptoms including very high fever, fast and irregular heartbeat, and breathing problems. It is believed that the tendency to develop malignant hyperthermia is inherited.
Dantrolene is available only with your doctor's prescription.
Before using dantrolene
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For dantrolene, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to dantrolene or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies have not been performed on the relationship of age to the effects of dantrolene in children below 5 years of age. Safety and efficacy have not been established.
No information is available on the relationship of age to the effects of dantrolene in geriatric patients.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking dantrolene, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using dantrolene with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Calcium Oxybate
- Chloral Hydrate
- Magnesium Oxybate
- Potassium Oxybate
- Sodium Oxybate
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of dantrolene. Make sure you tell your doctor if you have any other medical problems, especially:
- Heart disease or
- Liver disease, history of or
- Lung disease (e.g., emphysema, asthma, bronchitis)—The chance of serious side effects may be increased.
- Liver disease, active (e.g., hepatitis, cirrhosis) or
- Muscle spasms caused by rheumatic disorders—Should not be used in patients with these conditions.
Proper use of dantrolene
Dantrolene may be taken with or without food or on a full or empty stomach. However, if your doctor tells you to take the medicine a certain way, take it exactly as directed.
Take dantrolene only as directed by your doctor. Do not take more of it and do not take it more often than your doctor ordered.
The dose of dantrolene will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of dantrolene. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (capsules):
- For prevention or treatment of malignant hyperthermia:
- Adults—Dose is based on body weight and must be determined by your doctor. The usual dose is 4 to 8 milligrams (mg) per kilogram (kg) of body weight each day, and is divided in 3 or 4 doses. Your doctor will tell you exactly when and how often to take your medicine.
- Children—Use and dose must be determined by your doctor.
- To relieve muscle spasms:
- Adults—At first, 25 milligrams (mg) once a day. Your doctor may adjust your dose as needed. However, the dose is usually not more than 100 mg four times a day.
- Children—Dose is based on body weight and must be determined by your doctor. At first, 0.5 milligram (mg) per kilogram (kg) of body weight twice a day. Your doctor may adjust the dose as needed. However, the dose is usually not more than 3 mg per kg four times a day or 100 mg four times a day.
- For prevention or treatment of malignant hyperthermia:
If you miss a dose of dantrolene, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Ask your healthcare professional how you should dispose of any medicine you do not use.
Precautions while using dantrolene
If you will be taking dantrolene for a long time (e.g., several months at a time), your doctor should check your progress at regular visits. Blood tests will be needed to check for unwanted effects.
Dantrolene will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; other muscle relaxants; or anesthetics, including some dental anesthetics. Therefore, do not drink alcoholic beverages, and check with your doctor before taking any of the medicines listed above, while you are using dantrolene.
Dantrolene may cause drowsiness, dizziness or lightheadedness, vision problems, or muscle weakness in some people. Make sure you know how you react to dantrolene before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert, well-coordinated, and able to see well.
Dantrolene may make your skin more sensitive to sunlight. Use a sunscreen when you are outdoors. Avoid sunlamps and tanning beds.
Dantrolene side effects
Along with its needed effects, a medicine 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:
- Bloody or black, tarry stools
- bloody or dark urine
- bluish color changes in skin color
- changes in speech
- chest pain
- convulsions (seizures)
- decrease in frequency of urination
- decrease in urine volume
- difficult urination
- difficulty in moving
- difficulty in passing urine (dribbling)
- difficulty in swallowing
- fast, pounding, or irregular heartbeat or pulse
- increased frequency of urination
- increased urge to urinate during the night
- joint pain
- light-colored stools
- loss of bladder control
- mental depression
- muscle aching or cramping
- muscle pains or stiffness
- muscle spasm or jerking of all extremities
- nausea and vomiting
- pain in lower back
- pain or burning while urinating
- pain, tenderness, or changes in skin color
- painful urination
- severe stomach pain
- shortness of breath
- skin rash, hives, or itching
- slow or troubled breathing
- sudden decrease in amount of urine
- sudden loss of consciousness
- swelling of foot or leg
- swollen joints
- unusual tiredness or weakness
- upper right abdominal pain
- vomiting of blood or material that looks like coffee grounds
- waking to urinate at night
- yellow eyes or skin
Some side effects 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:
- general feeling of discomfort or illness
- muscle weakness
- Abdominal or stomach cramps or discomfort
- abnormal hair growth
- acne-like rash
- blurred or double vision or any change in vision
- change in taste
- chills and fever
- disturbed color perception
- excessive tearing
- halos around lights
- itching skin
- loss of appetite
- night blindness
- overbright appearance of lights
- redness of skin
- seeing double
- skin rash, encrusted, scaly and oozing
- slurring of speech or other speech problems
- sudden decrease in amount of urine
- trouble in sleeping
- tunnel vision
- unable to sleep
- unusual nervousness
- weight loss
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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- Drug class: skeletal muscle relaxants
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