Generic Name: chlorzoxazone (klor-ZOX-a-zone)
Medically reviewed by Drugs.com. Last updated on July 13, 2020.
Commonly used brand name(s)
In the U.S.
- Parafon Forte DSC
Available Dosage Forms:
Therapeutic Class: Skeletal Muscle Relaxant, Centrally Acting
Uses for chlorzoxazone
Chlorzoxazone is used to relax certain muscles in your body and relieve the discomfort caused by acute (short-term), painful muscle or bone conditions. However, chlorzoxazone does not take the place of rest, exercise, physical therapy, or other treatments that your doctor may recommend for your medical condition.
Chlorzoxazone is a skeletal muscle relaxant. It acts on the central nervous system (CNS) to relax muscles.
Chlorzoxazone is available only with your doctor's prescription.
Before using chlorzoxazone
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 chlorzoxazone, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to chlorzoxazone 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.
No information is available on the relationship of age to the effects of chlorzoxazone in the pediatric population. Safety and efficacy have not been established.
No information is available on the relationship of age to the effects of chlorzoxazone in geriatric patients. However, elderly patients are more likely to have age-related liver problems, which may require caution in patients receiving chlorzoxazone.
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 chlorzoxazone, 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 chlorzoxazone 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
- Gabapentin Enacarbil
- Magnesium Oxybate
- Morphine Sulfate Liposome
- Potassium Oxybate
- Sodium Oxybate
Using chlorzoxazone with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- St John's Wort
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 chlorzoxazone. Make sure you tell your doctor if you have any other medical problems, especially:
- Liver disease—Use with caution. May increase the risk of serious side effects.
Proper use of chlorzoxazone
The dose of chlorzoxazone 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 chlorzoxazone. 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 (tablets):
- For relaxing muscles:
- Adults—500 milligrams (mg) three or four times a day. Your doctor may adjust your dose if needed.
- Children—Use and dose must be determined by your doctor.
- For relaxing muscles:
If you miss a dose of chlorzoxazone, 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 chlorzoxazone
It is very important that your doctor check your progress at regular visits to make sure that chlorzoxazone is working properly and to check for unwanted effects.
Liver problems may occur while you are using chlorzoxazone. Stop using chlorzoxazone and check with your doctor right away if you are having more than one of these symptoms: abdominal pain or tenderness; clay-colored stools; dark urine; decreased appetite; fever; headache; itching; loss of appetite; nausea and vomiting; skin rash; swelling of the feet or lower legs; unusual tiredness or weakness; or yellow eyes or skin.
Chlorzoxazone will add to the effects of alcohol and other CNS depressants (medicines that make you drowsy or less alert). Some examples of CNS depressants are antihistamines or medicine for hay fever, allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; or anesthetics, including some dental anesthetics. Check with your medical doctor or dentist before taking any of these medicines while you are taking chlorzoxazone.
Chlorzoxazone 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.
Check with your doctor immediately if any of the following side effects occur:
- Bloody or black, tarry stools
- clay-colored stools
- dark urine
- decreased appetite
- difficulty swallowing
- fast heartbeat
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
- loss of appetite
- nausea and vomiting
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- severe stomach pain
- shortness of breath
- skin rash
- swelling of the feet or lower legs
- tightness in the chest
- unusual tiredness or weakness
- vomiting of blood or material that looks like coffee grounds
- yellow eyes or skin
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
- difficult or troubled breathing
- general feeling of discomfort or illness
- irregular, fast or slow, or shallow breathing
- pale or blue lips, fingernails, 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:
- large, flat, blue, or purplish patches in the skin
- small red or purple spots on the skin
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.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
More about chlorzoxazone
- Side Effects
- During Pregnancy
- Dosage Information
- Drug Images
- Drug Interactions
- Pricing & Coupons
- En Español
- 59 Reviews
- Drug class: skeletal muscle relaxants
- FDA Alerts (1)