Chlorzoxazone: uses, dosing, side effects & brands
Chlorzoxazone is a muscle relaxant sold in the U.S. under 3 brand and generic names, for muscle cramp, muscle rigidity and myositis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Muscle Relaxant
- Treats
- Muscle Cramp, Muscle Rigidity and Myositis
- Available as
- Tablet
- Sold as
- 3 products — Chlorzoxazone, Paraflex and Parafon Forte Dsc
- Prescription?
- Prescription only
- Generic available?
- Yes
- What the pharmacy pays
- about $16 for a 30-count supply — not your price
How chlorzoxazone is dosed
From the FDA label for Chlorzoxazone (application ANDA081298). Other chlorzoxazone products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
Usual Adult Dosage One tablet three or four times daily. If adequate response is not obtained with this dose, it may be increased to one and one-half tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Chlorzoxazone side effects
Chlorzoxazone containing products are usually well tolerated. It is possible in rare instances that chlorzoxazone may have been associated with gastrointestinal bleeding. Drowsiness, dizziness, lightheadedness, malaise, or over-stimulation may be noted by an occasional patient. Rarely, allergic type skin rashes, petechiae, or ecchymoses may develop during treatment. Angioneurotic edema or anaphylactic reactions are extremely rare. There is no evidence that the drug will cause renal damage. Rarely, a patient may note discoloration of the urine resulting from a phenolic metabolite of chlorzoxazone. This finding is of no known clinical significance. To report SUSPECTED ADVERSE EVENTS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876 or FDA at 1-800- FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.
Who shouldn’t take chlorzoxazone
Chlorzoxazone is contraindicated in patients with known intolerance to the drug.
Every chlorzoxazone product we track (3)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 70/100 | Prescription | Tablet | Generic | $16 | View → | |
| 2 | Not yet rated | Prescription | Tablet | Generic | $16 | View → | |
| 3 | Not yet rated | Prescription | Tablet | Generic | $16 | View → |
What chlorzoxazone pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
How long chlorzoxazone keeps
No chlorzoxazone label we read sets a separate limit for after opening, but they do specify how it must be stored — and the stability behind any date assumes those conditions.
Does chlorzoxazone expire? The in-use limits and storage rules from its labelsWhat people report to the FDA about chlorzoxazone
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 1,455 reports naming chlorzoxazone, and the FDA flagged 66% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- nausea108 reports
- dizziness106 reports
- fatigue106 reports
- headache90 reports
- anxiety74 reports
- dyspnoea64 reports
- diarrhoea60 reports
- chronic kidney disease59 reports
Read these as a signal, not a rate. A report does not mean chlorzoxazone caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved July 25, 2026.
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Frequently asked questions
What is chlorzoxazone?
Chlorzoxazone is a muscle relaxant used to treat Muscle Cramp, Muscle Rigidity, Myositis, Pain.
What kind of drug is chlorzoxazone?
The FDA classifies chlorzoxazone as a muscle relaxant. Most muscle relaxants work in the brain and spinal cord rather than on the muscle itself: they damp down the overactive nerve signals and reflexes that keep muscles tense, easing spasms and tightness. Some specialized agents instead act directly on muscle calcium release. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take chlorzoxazone with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run chlorzoxazone against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is chlorzoxazone sold under?
We track 3 chlorzoxazone-containing products in the U.S.: Chlorzoxazone, Paraflex and Parafon Forte Dsc. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does chlorzoxazone come in?
Across the brands we track, chlorzoxazone is currently marketed as tablet, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic chlorzoxazone?
Yes. Our catalog lists 1 generic chlorzoxazone product alongside the brand versions. A generic has the same active ingredient and must meet the FDA's bioequivalence standard; it usually costs less. Ask your pharmacist which one your plan covers.
Cite this page
- APA
- pharmaranks. (2026, July 24). Chlorzoxazone: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/chlorzoxazone
- MLA
- “Chlorzoxazone: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/chlorzoxazone.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for chlorzoxazone on DailyMed (NIH) ↗.