FDA-filed SPL labeling · retrieved through openFDA

Chlorzoxazone

Chlorzoxazone is a muscle relaxant tablet used alongside rest and physical therapy to relieve pain and discomfort from acute musculoskeletal conditions.

Brand names Parafon Forte DSCParaflexStrifon Forte DSCLorzone
Drug class ⓘ Muscle Relaxant
Rx Form 1 Route Oral
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 30 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

At a glance
Linked label effectiveSep 5, 2023
Clinical labels in scope ⓘ30
AvailabilityRx
Earliest approval/marketing year ⓘ1958
FDA-listed product records ⓘ97
Boxed warningNone found in compared labels
How we combine label and product data →
✓No current FDA shortage listed · checked Sep 22, 2026
⭐ Chlorzoxazone at a glance The quick version — the full detail is in the Patient Information Guide below.
💊
HelloPharmacist Editorial Team Bottom Line
Chlorzoxazone is a short-term oral muscle relaxant used with rest and physical therapy to ease acute muscle pain and spasm. It is generally well tolerated, but rare cases of serious liver damage have been reported — know the warning signs and stop the medication immediately if they appear. Avoid alcohol while taking it, and follow your prescriber's dosing guidance closely.
How we write & review this content — our editorial policy →

📖 Chlorzoxazone: Patient Information Guide

A plain-language walkthrough of Chlorzoxazone — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.

🎯What it's used for▾

Chlorzoxazone tablets are approved to help relieve pain and discomfort from acute musculoskeletal conditions — muscle spasms and the soreness that comes with them. It is always used as part of a broader treatment plan.

  • Relief of discomfort associated with acute, painful musculoskeletal conditions
  • Used alongside rest, physical therapy, and other supportive measures — not as a standalone treatment
⚙️How it works▾

Chlorzoxazone acts mainly at the spinal cord and the lower (subcortical) regions of the brain. It works by blocking the nerve reflex pathways — called multisynaptic reflex arcs — that create and sustain muscle spasms. Quieting those nerve signals helps reduce spasm, relieve pain, and improve movement in the affected muscles. Its sedative properties may also contribute to its effect, though the exact mechanism hasn't been fully pinpointed.

💊How it's taken▾

Chlorzoxazone tablets are taken by mouth, typically three or four times per day. Your prescriber may start you at a lower amount and increase it if your pain is not well controlled, then bring the dose back down as you improve. Always follow your prescriber's instructions exactly — the right amount depends on the specific tablet strength you are given.

  • Taken orally, multiple times daily
  • Dose may be adjusted up or down based on your response
  • Follow your prescription label; do not adjust the dose on your own
🤒Side effects — in detail▾

Most people tolerate chlorzoxazone well, but some side effects can occur:

  • Drowsiness, dizziness, or lightheadedness
  • Nausea or other stomach upset
  • Malaise (general unwell feeling)
  • Overstimulation (unusual restlessness)
  • Skin rash or unusual bruising (rare)
  • Orange or reddish-brown urine — caused by a harmless breakdown product of the drug

Rarely, serious allergic reactions (including swelling of the face or throat) or liver damage can occur. Stop the medication and get medical help right away if you notice signs of liver problems — fever, yellowing skin or eyes, dark urine, severe fatigue, or upper right abdominal pain.

⚠️Warnings & precautions▾

The most important risk is rare but serious: liver damage (hepatotoxicity), which can be fatal. It appears to be unpredictable and can happen in anyone, not just people with existing liver problems. Early warning signs include fever, rash, loss of appetite, nausea, vomiting, unusual tiredness, pain in the upper right abdomen, dark urine, or jaundice (yellow skin or eyes). Stop taking the medication immediately and contact your doctor if any of these develop.

  • Combining chlorzoxazone with alcohol or other CNS depressants (sleep aids, anxiety medications, opioids) increases sedation and can be dangerous.
  • Pregnancy safety has not been established — use only when your doctor decides the benefit clearly outweighs the risk.
  • Drowsiness and dizziness can affect your ability to drive or operate machinery safely.
🔀What it interacts with▾

Chlorzoxazone can interact with certain substances, potentially making side effects stronger or more dangerous:

  • Alcohol — adds to the sedative effect; avoid or limit alcohol while taking this medication
  • CNS depressants (such as sleep medications, anti-anxiety drugs, opioid pain relievers) — combining these with chlorzoxazone can intensify drowsiness and slow reflexes

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

📋Before taking it▾
  • Tell your doctor if you have ever had an intolerance or allergic reaction to chlorzoxazone.
  • Discuss your full medication list, especially any sleep aids, anxiety medications, or other sedating drugs.
  • If you are pregnant, planning to become pregnant, or could become pregnant, talk to your doctor — the safety of chlorzoxazone during pregnancy has not been established.
  • Use caution driving or operating heavy machinery — drowsiness and dizziness are possible side effects.
  • Let your doctor know if you have any history of liver problems, since chlorzoxazone carries a rare risk of liver damage.
🚑If you take too much▾

Taking too much chlorzoxazone can cause nausea, vomiting, diarrhea, drowsiness, dizziness, and headache. In more serious cases, it can cause significant muscle weakness, slowed or irregular breathing, and low blood pressure. If an overdose is suspected, seek emergency medical care immediately — treatment may include measures to remove the drug from the stomach and supportive care to protect breathing and blood pressure.

📡Pharmacodynamics — effects in the body▾

Chlorzoxazone reduces skeletal muscle spasm by acting on the spinal cord and subcortical brain regions, not by working directly on the muscles themselves. By interrupting the nerve reflex loops that sustain spasm, it helps restore movement and ease pain in the affected muscles. Its sedative properties may also contribute to overall symptom relief.

🔬Pharmacokinetics — how your body processes it▾

After you take a chlorzoxazone tablet by mouth, it is absorbed quickly — detectable in the blood within the first 30 minutes, with peak levels reached in about 1 to 2 hours in most people. The drug is rapidly broken down (metabolized) and leaves the body mainly through the urine, mostly in a processed (conjugated) form. Less than 1% of the drug is excreted unchanged, meaning the body clears it efficiently.

📦How to store it▾

Dispense in tight container as defined in the official compendium. Store at 20° to 25° C (68° to 77° F) .

📄 Written from Chlorzoxazone’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →

26

Supplements & herbs that interact with Chlorzoxazone

26 supplements and herbal products have documented interactions with Chlorzoxazone in the licensed clinical database we use. Most are manageable — but your pharmacist should know about everything you take, including vitamins and herbals.

Severity mix
  • Major · 2
  • Moderate · 15
  • Minor · 9
ACTIVATED CHARCOAL Major PROCAINE Major COFFEE CHARCOAL Moderate DIOSMIN Moderate EUROPEAN MANDRAKE Moderate EVODIA Moderate GLUCOMANNAN Moderate GUAR GUM Moderate +18 more
Every supplement checked against Chlorzoxazone — ranked by severity The full interaction hub: 2 major · 15 moderate · 9 minor · every one linked to its full report. Check Chlorzoxazone against your exact supplements

Educational information from a licensed clinical database (Natural Medicines) — see our data sources & update cadence. Not medical advice: an interaction being documented does not mean it will happen to you; do not start or stop medications or supplements without professional guidance.

🩺 Pharmacist Counseling Corner

Quick, plain-English answers to the questions patients ask most about Chlorzoxazone — the kind of thing our pharmacy team would talk through with you at the counter.

What exactly is chlorzoxazone used for? ▾
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 with rest and physical therapy, not on its own. Think of it as one part of a bigger recovery plan.
Will this make me drowsy? Is it safe to drive? ▾
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 drowsiness significantly worse, so it's important to avoid or strictly limit drinking while you're taking this medication.
My urine looks orange or reddish — should I be worried? ▾
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 clinical significance and should not alarm you. That said, if your urine turns dark brown rather than orange, contact your doctor, as dark urine can occasionally signal a liver issue.
What are the warning signs I should actually watch out for? ▾
The most important thing to watch for is signs of liver problems — fever, loss of appetite, nausea, fatigue, pain in the upper right side of your belly, dark urine, or yellowing of your skin or eyes. These are rare, but if you notice any of them, stop taking chlorzoxazone right away and call your doctor. Don't wait to see if it gets better on its own.
Can I take this if I'm pregnant or trying to get pregnant? ▾
The safety of chlorzoxazone during pregnancy hasn't been established. Your doctor should make a careful call about whether the benefit to you outweighs any potential risk. If you're pregnant, trying to conceive, or think you might be pregnant, make sure your prescriber knows before you start taking it.
Can I take chlorzoxazone with my other medications? ▾
It depends on what else you're taking. Chlorzoxazone can add to the sedating effects of other medications that slow the nervous system — like sleep aids, anxiety medications, or opioid pain relievers. Make sure your prescriber and pharmacist know everything you're taking so they can check for any concerns before you start.
Is Chlorzoxazone available over the counter? ▾
Chlorzoxazone is dispensed by prescription according to its FDA labeling, so it isn't sold over the counter. Your prescriber and pharmacist will determine if it's appropriate for you.
When was Chlorzoxazone first available? ▾
Chlorzoxazone has been available in the United States since at least 1958, based on FDA approval history (Drugs@FDA) and product marketing records.
Who makes Chlorzoxazone? ▾
Chlorzoxazone is supplied by 40 manufacturers listed in the FDA NDC Directory, including Bryant Ranch Prepack, Rising Pharma Holdings, Inc., Aurobindo Pharma Limited.

💬 Answers drafted from Chlorzoxazone’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →

🧰 Keep exploring

📊Chlorzoxazone supplement interactions26 checked — ranked by severity 🌿Drug & Supplement CheckerChlorzoxazone vs. vitamins & herbs 💬Ask a PharmacistFree answer, usually < 24h 🔎NDC & pricing lookupFind Chlorzoxazone NDCs & costs 🅰️Browse Drugs A–ZLook up any medication

💊 How Chlorzoxazone comes

Chlorzoxazone is available in 1 form. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Tablet

By mouth
Brands Lorzone
How this form is used
What it may be used for
  • Used to relieve discomfort from acute, painful musculoskeletal conditions as an adjunct to rest and physical therapy
Important instructions
  • Take by mouth three or four times daily as directed by your prescriber
  • Your prescriber may increase the dose if your response is inadequate, then reduce it as you improve
  • Follow the specific instructions on your prescription label — the right amount depends on the tablet strength prescribed
Available strengths 4 strengths
250 mg 375 mg 500 mg 750 mg
92 FDA-listed product records ⓘ

📊 Chlorzoxazone across the U.S. market

How Chlorzoxazone appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

1
Dose forms ⓘ
40
Manufacturers
2
Brand names
97
FDA-listed product records ⓘ
1958
First marketed ⓘ

Also listed with the FDA, not a patient dose form: Powder (5) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.

Bryant Ranch Prepack11%
Rising Pharma Holdings, Inc.8%
Aurobindo Pharma Limited7%
A-S Medication Solutions5%
Actavis Pharma, Inc.4%
Vertical Pharmaceuticals, Inc.4%
Other makers60%

Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

📈 How widely Chlorzoxazone is used

A general measure of how commonly Chlorzoxazone is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.

Think of this as a proxy for how widely Chlorzoxazone is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.

30,247
Medicaid prescriptions filled (Q1–Q4 2025)
$12.4M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Chlorzoxazone prescribed? Of the 1,596 medications we measure, Chlorzoxazone ranks #736 by Medicaid prescriptions — more than 54% of them.

Where Chlorzoxazone ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5
Total prescriptions — #736 of 1,596
#731 Tazarotene Topical 31,374 Rx #732 Atovaquone and Proguan... 31,273 Rx #733 Meropenem Injection 31,115 Rx #734 Meropenem 31,115 Rx #735 Triazolam 30,954 Rx #736 Chlorzoxazone 30,247 Rx #737 Fluorouracil Topical 30,176 Rx #738 Febuxostat 30,153 Rx #739 Isoniazid 30,009 Rx #740 Capecitabine 29,934 Rx #741 Thiamine (Vitamin B<su... 29,550 Rx

Utilization by Chlorzoxazone product

Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.

The 500 mg oral tablet is the most-dispensed Chlorzoxazone product — about 56% of these Medicaid prescriptions.

chlorzoxazone 500 MG Oral Tablet Most dispensed

17,065 Medicaid prescriptions (Q1–Q4 2025) 56% of Chlorzoxazone prescriptions shown $370,431 gross reimbursement (before rebates) ≈ $22 per prescription (gross)

Summed across the 6 of 129 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 197502

chlorzoxazone 250 MG Oral Tablet

10,111 Medicaid prescriptions (Q1–Q4 2025) 33% of Chlorzoxazone prescriptions shown $11.5M gross reimbursement (before rebates) ≈ $1,137 per prescription (gross)

Summed across the 3 of 15 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 197501

chlorzoxazone 375 MG Oral Tablet

2,465 Medicaid prescriptions (Q1–Q4 2025) 8% of Chlorzoxazone prescriptions shown $439,733 gross reimbursement (before rebates) ≈ $178 per prescription (gross)

Summed across the 4 of 15 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1088934

chlorzoxazone 750 MG Oral Tablet

606 Medicaid prescriptions (Q1–Q4 2025) 2% of Chlorzoxazone prescriptions shown $86,470 gross reimbursement (before rebates) ≈ $143 per prescription (gross)

Summed across the 3 of 16 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1088936

Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.

Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Chlorzoxazone, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 16 of 175 listed Chlorzoxazone NDCs with Medicaid activity.

🔍 Compare Chlorzoxazone products

A representative set of FDA-listed product records for Chlorzoxazone — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)

Showing 97 of 97 products — FDA National Drug Code Directory. See every product, package size and price: browse all 97 Chlorzoxazone NDCs →

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Chlorzoxazone RxCUI 2410 1 dose form · 4 strengths
  1. Dose form (SCDF) Oral Tablet RxCUI 371473 In current FDA listings
    Clinical drug / strength (SCD) 250 MG RxCUI 197501 375 MG RxCUI 1088934 500 MG RxCUI 197502 750 MG RxCUI 1088936

Look up RxCUI 2410 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

🏷️ Sold under these brand names

Parafon Forte DSC Paraflex Strifon Forte DSC Lorzone

🏭 Manufacturers & labelers

Bryant Ranch Prepack 11 Rising Pharma Holdings, Inc. 8 Aurobindo Pharma Limited 7 A-S Medication Solutions 5 Actavis Pharma, Inc. 4 Vertical Pharmaceuticals, Inc. 4 Trigen Laboratories, LLC 4 Cameron Pharmaceuticals 3 Advanced Rx of Tennessee, LLC 3 Solubiomix 3 Proficient Rx LP 3 PD-Rx Pharmaceuticals, Inc. 3 Cintex Services, LLC 3 i3 Pharmaceuticals, LLC 2 TruPharma, LLC 2 Advanced Rx Pharmacy of Tennessee, LLC 2 Quality Care Products, LLC 2 St. Mary's Medical Park Pharmacy 2 RPK Pharmaceuticals, Inc. 2 Par Health USA, LLC 2 Par Pharmaceutical, Inc. 2 Endo USA, Inc. 2 AXIS Pharmaceutics Inc 1 Direct Rx 1

…and 16 more on the FDA NDC directory.

RxNorm drug class

Chlorzoxazone belongs to the Muscle Relaxant class.

Pharmacologic class Muscle Relaxant
Drug family (ATC) Oxazol, thiazine, and triazine derivatives

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

🔬 Where this comes from

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Sep 5, 2023
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Chlorzoxazone.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Chlorzoxazone after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
30
NDC products indexed
97
Distinct labelers/manufacturers represented
40
Linked representative label ⓘ
Aurobindo Pharma Limited
Linked label effective
Sep 5, 2023
Composite sections available
11
Linked SPL Set ID
52d3aa2c-f88f-4de7-b5ae-df8a46e94879
Linked SPL Document ID
13956b60-a22d-4ee8-af95-460830ebfbc9
Open the linked representative label on DailyMed ↗

How we combine label and product data

HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 30 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.

For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Aurobindo Pharma Limited is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.

This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.