CHLORZOXAZONE 500 mg Tablet, 60-count
🆔 Identity & classification
Where does this data come from?
🏷️ RxNorm drug class
This medicine belongs to the Muscle Relaxant class.
Where does this data come from?
🏭 Manufacturer & labeler
Where does this data come from?
🩺 Clinical
Chlorzoxazone is used to relieve pain and stiffness caused by muscle strains and sprains. It is used in combination with physical therapy, analgesics (such as aspirin or acetaminophen), and rest.
Read the full MedlinePlus article ↗- Chlorzoxazone is a muscle relaxant used to help with short-term muscle pain and spasms — the kind that comes on suddenly from an injury or strain. It's meant to be used together wi...
- Yes, drowsiness and dizziness are real possibilities with chlorzoxazone. Until you know how it affects you, it's best to avoid driving or operating machinery. Alcohol makes the dro...
- Will this make me drowsy? Is it safe to drive?
- This is actually a known and harmless side effect. Chlorzoxazone breaks down into a substance that can temporarily color your urine orange or reddish-brown. It has no known clinica...
Patient education
Supplement & herbal interactions
Some supplements/herbs that may interact with Chlorzoxazone — tap one for details:
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💊 What it looks like
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🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
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Anhydrous lactose is a milk sugar with no water content. It acts as a filler and binder in tablets and capsules, adding bulk and helping ingredients stick together.
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UNII M28OL1HH48
Croscarmellose sodium is a plant-based substance derived from cellulose. It acts as a disintegrant, helping tablets and capsules break down quickly in the digestive system so the medicine can be absorbed.
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Docusate sodium is a stool softener compound that helps medicines dissolve and move through the digestive tract. It acts as a surfactant, reducing surface tension in the intestines, and also serves as a wetting agent in tablet formulations.
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Magnesium stearate is a salt made from magnesium and stearic acid, a fatty substance. It's used in tablets and capsules as a lubricant and glidant to help ingredients flow smoothly during manufacturing and prevent sticking.
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Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
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Sodium benzoate is a salt derived from benzoic acid, a preservative. It's added to medicines to prevent growth of bacteria, fungi, and other microorganisms that could spoil the product.
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A plant-based carbohydrate derived from corn kernels. It acts as a filler to add bulk, a binder to hold ingredients together, and a disintegrant to help the tablet break apart in your stomach for absorption.
7 inactive ingredients listed in the exact product block matched to this NDC.
Where does this data come from?
ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
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💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per each | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | Not in the retail survey — common for institutional, discontinued, or low-volume packs. | |
| Medicaid paysCMS SDUD · 12 mo | No recent Medicaid claims on file for this NDC — rare and low-volume NDCs are suppressed in the public data. | |
| Medicare drug plans payPart D · Q2 2026 | $0.2693 | $16.16 / 60 tablets |
Where does this data come from?
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Chlorzoxazone 500 mg 00591-2520-01 | Actavis | 100 tablets | $0.212 | AA | Availability likely | — |
| Chlorzoxazone 500 mg 16571-0726-01 | Rising | 100 tablets | $0.212 | AB | Availability likely | — |
| Chlorzoxazone 500 mg 59651-0306-01 | Aurobindo | 100 tablets | $0.212 | — | Availability likely | — |
| Chlorzoxazone 500 mg 70954-0085-10 | Novitium | 100 tablets | $0.212 | AA | Availability likely | — |
| Chlorzoxazone 500 mg 24470-0940-10 | Cintex | 100 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 50090-0315-00 | A-S | 30 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 50090-7504-00 | A-S | 30 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mg 51862-0339-01 | Mayne | 100 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mg 55289-0633-10 | PD-Rx | 10 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 63187-0317-20 | Proficient | 20 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 63629-1586-01 | Bryant | 20 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 70518-4364-00 | REMEDYREPACK | 90 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mg 71205-0711-30 | Proficient | 30 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mg 71335-1914-01 | Bryant | 20 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 71335-2009-01 | Bryant | 20 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mg 71335-2433-01 | Bryant | 20 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mg 71335-3122-00 | Bryant | 10 tablets | — | AA | FDA listed | — |
| Chlorzoxazone 500 mg 80425-0315-01 | Advanced | 30 tablets | — | AB | FDA listed | — |
| Chlorzoxazone 500 mgthis 80425-0507-02 | Advanced | 60 tablets | — | AB | FDA listed | — |
Where does this data come from?
⏳ Availability & generic status
This product is an FDA-approved generic. Other versions of the same drug are listed under Therapeutic equivalents, least expensive first.
Where does this data come from?
📊 Medicare Part D spend CMS · PART D · 2026 (Q1)
🔬 Reported adverse events (FAERS)
Top reported reactions
Age at onset
Reporter sex
Serious outcomes
Where does this data come from?
📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 80425-0507-01 | 30 TABLET in 1 BOTTLE (80425-0507-1) | 2025-03-20 | Active |
| 80425-0507-02 You're viewing this | 60 TABLET in 1 BOTTLE (80425-0507-2) | 2025-03-20 | Active |
| 80425-0507-03 | 90 TABLET in 1 BOTTLE (80425-0507-3) | 2025-03-20 | Active |
You're viewing one of 3 pack sizes for this product.
Pack size FAQ
What quantity is in NDC 80425-0507-02?
What is the difference between NDC 80425-0507-02 and NDC 80425-0507-01?
What NDC number is used to bill for this package of CHLORZOXAZONE 500 mg Tablet?
🧭 About this NDC listing & data coverage
What data is (and isn’t) available for this NDC — tap to expand
| NDC identity (package / product / labeler codes) | ✓ Available |
| Labeler | ✓ Available |
| Product & package description | ✓ Available |
| Marketing category & status | ✓ Available |
| Active ingredient / dosage form / route | ✓ Available |
| FDA label (SPL via DailyMed) | ✓ Available |
| Package photos | ✓ Available |
| Inactive ingredients (structured) | ✓ Available |
| NADAC pharmacy acquisition price (CMS) | — Not published for this NDC CMS publishes NADAC only for NDCs reported in its retail-pharmacy survey. |
| Orange Book / therapeutic-equivalence data | ✓ Available |
| HCPCS J-code billing crosswalk | — Not published for this NDC Most self-administered / retail products have no J-code — that is normal. |
| Medicaid utilization (CMS SDUD) | — Not published for this NDC CMS reports utilization only for NDCs with Medicaid claims above its privacy threshold. |
Questions about this listing
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📄 Full prescribing information FDA SPL
🎯 Indications and Usage ▾
INDICATIONS AND USAGE Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.
⏱️ Dosage and Administration ▾
DOSAGE AND ADMINISTRATION Usual Adult Dosage Chlorzoxazone tablets 375 mg: One tablet three or four times daily. If adequate response is not obtained with this dose, the 375 mg tablets may be increased to two tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Chlorzoxazone tablets 500 mg: 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 tablets 750 mg: 1/3 tablet (250 mg) three or four times daily. Initial dosage for painful musculoskeletal conditions should be 2/3 tablet (500 mg) three or four times daily. If adequate response is not obtained with this dose, it may be increased to one tablet (750 mg) three or four times daily.
As improvement occurs dosage can usually be reduced.
⛔ Contraindications ▾
CONTRAINDICATIONS Chlorzoxazone is contraindicated in patients with known intolerance to the drug.
⚠️ Warnings ▾
WARNINGS Serious (including fatal) hepatocellular toxicity has been reported rarely in patients receiving chlorzoxazone. The mechanism is unknown but appears to be idiosyncratic and unpredictable. Factors predisposing patients to this rare event are not known.
Patients should be instructed to report early signs and/or symptoms of hepatotoxicity such as fever, rash, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, or jaundice. Chlorzoxazone should be discontinued immediately and a physician consulted if any of these signs or symptoms develop. Chlorzoxazone use should also be discontinued if a patient develops abnormal liver enzymes (e.g., AST, ALT, alkaline phosphatase and bilirubin).
The concomitant use of alcohol or other central nervous system depressants may have an additive effect. Usage in Pregnancy: The safe use of chlorzoxazone has not been established with respect to the possible adverse effects upon fetal development. Therefore, it should be used in women of childbearing potential only when, in the judgement of the physician, the potential benefits outweigh the possible risks.
🤒 Adverse Reactions ▾
ADVERSE REACTIONS Chlorzoxazone containing products are usually well tolerated. It is possible in rare instances that chlorzoxazone may have been associated with gastrointestinal bleeding. Drowsiness, dizziness, light-headedness, malaise, or overstimulation 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 REACTIONS, contact Rising Pharma Holdings, Inc. at 1-844-874-7464 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
🆘 Overdosage ▾
OVERDOSAGE Symptoms: Initially, gastrointestinal disturbances such as nausea, vomiting, or diarrhea together with drowsiness, dizziness, lightheadedness or headache may occur. Early in the course there may be malaise or sluggishness followed by marked loss of muscle tone, making voluntary movement impossible. The deep tendon reflexes may be decreased or absent.
The sensorium remains intact, and there is no peripheral loss of sensation. Respiratory depression may occur with rapid, irregular respiration and intercostals and substernal retraction. The blood pressure is lowered, but shock has not been observed.
Treatment: Gastric lavage or induction of emesis should be carried out, followed by administration of activated charcoal. Thereafter, treatment is entirely supportive. If respirations are depressed, oxygen and artificial respiration should be employed and a patent airway assured by use of an oropharyngeal airway or endotracheal tube.
Hypotension may be counteracted by use of dextran, plasma, concentrated albumin or a vasopressor agent such as norepinephrine. Cholinergic drugs or analeptic drugs are of no value and should not be used.
🧬 Clinical Pharmacology ▾
CLINICAL PHARMACOLOGY Chlorzoxazone is a centrally-acting agent for painful musculoskeletal conditions. Data available from animal experiments as well as human study indicate that chlorzoxazone acts primarily at the level of the spinal cord and subcortical areas of the brain where it inhibits multisynaptic reflex arcs involved in producing and maintaining skeletal muscle spasm of varied etiology. The clinical result is a reduction of the skeletal muscle spasm with relief of pain and increased mobility of the involved muscles.
Blood levels of chlorzoxazone can be detected in people during the first 30 minutes and peak levels may be reached, in the majority of the subjects, in about 1 to 2 hours after oral administration of chlorzoxazone. Chlorzoxazone is rapidly metabolized and is excreted in the urine, primarily in a conjugated form as the glucuronide. Less than one percent of a dose of chlorzoxazone is excreted unchanged in the urine in 24 hours.
📦 How Supplied / Storage and Handling ▾
HOW SUPPLIED Chlorzoxazone tablets, USP are supplied as follows: 500 mg White to off white capsule shaped tablet, debossed with a break line between “1 and 2” on one side and plain on other side. Bottle of 30 Tablets NDC: 80425-0507-01 Bottle of 60 Tablets NDC: 80425-0507-02 Bottle of 90 Tablets NDC: 80425-0507-03 Dispense in tight container as defined in the official compendium. Store at 20° to 25° C (68° to 77° F) [see USP Controlled Room Temperature].
📋 Description ▾
For Painful Musculoskeletal Conditions PRESCRIBING INFORMATION DESCRIPTION Each 375 mg Chlorzoxazone tablet contains: Chlorzoxazone USP 375 mg. Each 500 mg Chlorzoxazone tablet contains: Chlorzoxazone USP 500 mg. Each 750 mg Chlorzoxazone tablet contains: Chlorzoxazone USP 750 mg.
Chemical Name: 5-Chloro-2-benzoxazolinone. Structural Formula: Molecular Formula: C 7 H 4 CINO 2 Molecular Weight: 169.56 Chlorzoxazone USP is a white or practically white, practically odorless, crystalline powder. Chlorzoxazone is slightly soluble in water; sparingly soluble in alcohol, in isopropyl alcohol, and in methanol; soluble in solutions of alkali hydroxides and ammonia.
Inactive ingredients: anhydrous lactose, croscarmellose sodium, docusate sodium with sodium benzoate, magnesium stearate, microcrystalline cellulose and pregelatinized maize starch. FDA approved dissolution test specifications differ from USP . struct