Chlorzoxazone Side Effects
Not all side effects for chlorzoxazone may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.
For the Consumer
Applies to chlorzoxazone: oral capsule, oral tablet
In addition to its needed effects, some unwanted effects may be caused by chlorzoxazone. In the event that any of these side effects do occur, they may require medical attention.
You should check with your doctor immediately if any of these side effects occur when taking chlorzoxazone:Rare
- 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
If any of the following symptoms of overdose occur while taking chlorzoxazone, get emergency help immediately: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 of the side effects that can occur with chlorzoxazone may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:Rare
- large, flat, blue, or purplish patches in the skin
- small red or purple spots on the skin
For Healthcare Professionals
Applies to chlorzoxazone: compounding powder, oral tablet
Gastrointestinal side effects of chlorzoxazone have rarely included gastrointestinal bleeding.
Nervous system side effects have included drowsiness, dizziness, light-headedness, malaise, and overstimulation.
Hypersensitivity side effects have rarely included skin rashes, petechiae, angioneurotic edema, anaphylactic reactions, and ecchymoses.
Renal side effects attributed to a phenolic metabolite have rarely included urine discoloration.
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