Chlorzoxazone (Oral)

Chlorzoxazone is a muscle relaxer that is also known by the brand name Lorzone.


The drug chlorzoxazone is only available by a prescription and is intended to be taken to relax muscles. This medication can be prescribed for a variety of reasons such as back injury or another condition that creates tense, or painful muscles in the body. Always use caution when taking this medication. Keep it out of reach of children and pets. If you have any medical conditions or diseases, you should talk to your doctor before beginning this medication. There is a possibility this medication may pose a risk of disease or drug interaction. You should also inform your health care provider if you take herbal supplements or vitamins.

This medication is intended for use in adults over the age of 18. Anyone under the age of 18 should be under the strict supervision of their healthcare provider. Do not use this medication with alcohol. Do not store this medication with other medications. If you develop any side effects or begin to experience swelling of the tongue, mouth, lips, face, or extremities, you should alert your healthcare provider and seek emergency treatment for an allergic reaction to chlorzoxazone.

If you plan to travel with this medication, you should keep it in the same container it came in. Do not store this medication in areas that have excessive moisture such as the bathroom. Do not flush this medication down the toilet. If you must discard it, you should bring it to your local community take-back program or follow the FDA's instruction on how to properly dispose of drugs. If you add any medications to your routine, you should immediately inform your healthcare provider to help eliminate the chance of side effects and interactions. If you experience life-threatening reactions or side effects, you should seek emergency medical assistance.

Condition treated

  • Tense or painful muscles

Type of medicine

  • Muscle relaxer

Side Effects

Chlorzoxazone is known to have the potential to cause a variety of unpleasant, and sometimes life-threatening conditions. If you experience a serious side effect or feel that you are having an allergic reaction, you should notify your doctor and seek medical attention. Do not take more than the recommended dose of this drug, and do not double your dose if forget to take it. This drug is not intended for pediatric use and should only be used under the close supervision of your doctor if you are pregnant or nursing. Tell your doctor about any pre-existing conditions before taking chlorzoxazone and tell them all of the medications and supplements you are currently taking.

Black, tarry, or bloody stool

Monitor your stool when taking this medication. If you notice it turning black in color or an unusual consistency, you should alert your health care provider because it may indicate an intolerance or a developing underlying medical condition.

Loss of appetite

You may notice that your appetite decreases when taking this drug. If this persists past the adjustment phase, you may require a dose adjustment or a change in your treatment plan.

Clay-colored stool

A clay-colored stool may indicate a problem with your body processing this medication properly and should be monitored closely by your doctor.

vomiting or nausea

In some instances, people who take this drug may feel nauseated. This is also a sign of overdose and allergic reaction so you should seek medical treatment immediately.


If you have constipation, you should ask your doctor what you can take or do to alleviate this mild side effect.


Developing a cough from using this medication is rare. I can be a result of an intolerance, or it can be a sign of an underlying developing medical condition.

Swelling of the face, eyelids, lips, or tongue

Any swelling of the face, lips, tongue, lips, or eyelids is the sign of a serious allergic reaction that should be treated immediately because it is a life-threatening condition.

Stomach pain

Stomach pain can signal a serious medical issue that requires immediate medical attention.

Shortness of breath

Shortness of breath can indicate an allergic reaction or intolerance to chlorzoxazone.

Decreased appetite

A decreased appetite that persists for an extended period of time may prompt a dose adjustment.

Dark urine

You may notice dark urine when taking this drug. Keep your health care provider informed about this side effect.


A rash is a sign of intolerance or could be caused by a preexisting condition interacting with this drug.

Difficult swallowing

If have trouble swallowing you may be having an allergic reaction to chlorzoxazone.


This medication can cause dizziness, especially during the first few weeks of taking chlorzoxazone. If this condition persists or gets worse, you may need a dose adjustment or a change of medication.

Fast heartbeat

A fast heartbeat can be a sign of an overdose or an adverse reaction.


If you develop a fever, you may be having a serious side effect. It is also possible that you are developing an underlying medical condition.

Tight chest

If you feel a tightness in your chest when taking this drug, you may be having an allergic reaction, a severe side effect, or an underlying medical condition.

Tiredness or weakness

Tiredness is common when taking chlorzoxazone, but if this condition persists or is accompanies by unexplained weakness you should find out what your alternative treatment options are.


If you notice hives on your skin, it is a sign of an allergic reaction.

Vomiting blood or coffee ground-like material

If you vomit blood or material similar to coffee grounds, you should seek emergency medical treatment for a potentially life-threatening situation.


Wheezing is a sign of an allergic reaction or an overdose and requires emergency medical treatment.

Yellow eyes or skin

If you notice yellowing of the eyes or the skin, it can indicate hepatic failure and should be treated immediately.


Itching is uncommon when taking this drug. If you begin to notice your skin becoming itchy, you should consult with your doctor about altering your dose or finding an alternative treatment.

Hives like swelling of the face, mouth, extremities, and sex organs

If you develop a rash that resembles hives and features swelling, you should seek medical treatment for a possible life-threatening condition such as allergic reactions.

Overdose symptoms:

  • Trouble breathing
  • Diarrhea
  • Feeling ill
  • General discomfort
  • Drowsiness
  • Irregular breathing
  • Headache
  • Lightheaded
  • Nausea
  • Blue skin or lips
  • Vomiting
  • Sluggish


The dose recommended for an adult treating muscle spasm is 125 to 500 mg orally of chlorzoxazone 3 to 4 times per day orally. This medication may also be divided up as 20 mg doses up to 3 to 4 times per day. There is not renal adjustment dose, and is not recommended for people who have a liver impairment.


There are a total of 651 known drug interactions associated with chlorzoxazone. Of these 651 drug interactions, 132 are major drug interactions, 515 are moderate drug interactions, and 4 are minor drug interactions. The most common drugs known to interact with chlorzoxazone are Ambien, Prozac, Topamax, Benadryl, Vicodin, Cymbalta, Lyrica, Xanax, Norco, Oxycontin, and Zyrtec.

Food/Lifestyle interaction:


Avoid consuming alcohol when taking chlorzoxazone because it increases the risk of side effects and can cause dizziness, trouble concentrating, and drowsiness. Do not operate a vehicle when consuming alcohol and taking this medication.

Disease interaction:


This medication has been known in some cases to cause a condition called idiosyncratic hepatocellular toxicity. If you have any liver impairment or conditions, you should tell your doctor so they can monitor your condition for changes. If you have any signs of hepatic injury, you should report them immediately and seek emergency medical attention.


You should tell your doctor about any pre-existing conditions you have, especially if you have liver disease, heart disease, or diabetes. If you are pregnant or nursing you should consult your doctor and only take this medication if instructed to do so. If you experience any side effects you should report your condition to your health care provider and seek emergency medical treatment especially if it is a life-threatening condition.

Do not take this medication with alcohol because it can increase your chance of developing side effects. Keep this medication out of the reach of others, children, and pets. Store your medication in the original bottle and do not store other medications in the same container as chlorzoxazone.


Store this medication in a locking container, preferably the original container it came in, especially if you plan to travel. Do not store this medication near light or heat. Keep this drug away from areas that may have excessive moisture such as the bathroom. Do not take this medication if it is expired. If you must dispose of this medication, you should take it to your community take-back program or dispose of it using the FDA's guidelines for proper drug disposal.


Chlorzoxazone is a medication that is used to help relax muscles. It is used for a wide variety of medical conditions and should only be taken by an adult age 18 or older, unless under the strict supervision of a doctor. This medication is known to have several interaction risks, which is why you should thoroughly discuss your medical history, and any medication and supplements you take to help reduce the risk of side effects. This medication should be stored out of the reach of others, particularly children, and pets. Only take this medication in single doses to avoid the risk of overdose and side effects. This medication is only intended to relieve muscle and joint pain for a short period of time and is not a cure for any condition.

Do not take this medication if you are pregnant or nursing unless under the supervision of your doctor. Do not drink alcohol with this medication because it can cause amplified impairment and an increased chance of side effects. This medication is not intended for pediatric use unless specified by your doctor. Do not take more of this medication than indicated by your doctor because you can develop liver toxicity or you may overdose.

Meta description: Chlorzoxazone is a medication that is used to relax muscles for a variety of medical condition and is intended for adult use.