Prescription medication · Muscle Relaxant
chlorzoxazone
Also sold as Parafon Forte. This medicine treats discomfort from muscle problems.
Data updated 2026-05-15
- 1,256
- FDA reportsRarely reported
- 1
- InteractionFew interactions
- $0.19
- Generic price (NADAC)
What the data shows
chlorzoxazone (Parafon Forte) is a prescription Muscle Relaxant, among the least-reported drugs the FDA tracks (1,256 FDA reports), with 1 documented drug interaction.
Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.
chlorzoxazone (Parafon Forte) is a prescription Muscle Relaxant. This medicine treats discomfort from muscle problems.
Chlorzoxazone is a muscle relaxant. It helps to relieve discomfort from painful muscle problems.
Verify with FDA → · CMS NADAC pricing →
Drug Pricing (NADAC)
Generic Price
$0.19/unit
Generic Available
Yes (11 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
This medicine treats discomfort from muscle problems.
Common side effects
Drowsiness, Dizziness, Lightheadedness
Key warnings
If you are intolerant to chlorzoxazone, you should not take this medicine.
The sections below are summarized in plain English from chlorzoxazone's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.
How It Works
The way this drug works is not fully known. It may work by making you feel sleepy. This medicine does not directly relax your muscles.
How to Take It
Take one tablet three or four times each day. If that doesn't help enough, your doctor may increase your dose to one and a half tablets (750 mg) three or four times a day. Your doctor will lower your dose as you start feeling better.
This is a plain-language summary of chlorzoxazone's FDA labeling, not individualized dosing advice. Ask a pharmacist or prescriber before changing how you take this medication.
Pregnancy & Breastfeeding
Talk to your doctor if you are pregnant or breastfeeding. It is not known if this medicine will harm your unborn baby. It is also not known if this medicine passes into breast milk.
This is a plain-language summary of chlorzoxazone's FDA labeling, not individualized advice. Ask a pharmacist or prescriber about pregnancy or breastfeeding on this medication.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is close to your next dose, skip the missed dose and continue with your regular schedule.
This is a plain-language summary of chlorzoxazone's FDA labeling, not individualized advice. Ask a pharmacist or prescriber what to do about your specific missed dose.
Storage
Store at room temperature between 59° and 86°F.
Side Effects (from patient reports)
Based on 1,256 FDA adverse event reports.
Most-reported reactions
Adverse reactions in FAERS for chlorzoxazone, by number of reports
- Feeling unsteady or lightheaded
Feeling unsteady or lightheaded
94 reports
- Feeling sick to your stomach
Feeling sick to your stomach
94 reports
- Feeling very tired
Feeling very tired
92 reports
- General discomfort
General discomfort
90 reports
- Pain in your head
Pain in your head
72 reports
- Feeling worried or nervous
Feeling worried or nervous
66 reports
- Long-term kidney problems
Long-term kidney problems
56 reports
- Loose, watery stools
Loose, watery stools
53 reports
- Feeling sleepy or drowsy
Feeling sleepy or drowsy
51 reports
- Difficulty breathing
Difficulty breathing
47 reports
What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.
Reports over time
Adverse-event reports filed for chlorzoxazone each year to the FDA Adverse Event Reporting System (FAERS).
Year-to-year volume tracks usage, prescribing, and scrutiny, not a change in per-patient risk. Source: FDA FAERS.
Where chlorzoxazone sits
chlorzoxazone has more FDA adverse-event reports than 8% of the drugs FAERS tracks. A high position reflects how widely a drug is used and watched, not how dangerous it is.
Percentile across all drugs PlainMeds tracks by FAERS report volume. The dot is chlorzoxazone; the line is the median (50th percentile).
FDA Adverse Event Report Analysis
Detailed analysis of 1,256 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
1,256
Reports Mentioning Death
130
10.4% of reports — not proof of cause
Hospitalization Reports
346
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | DIZZINESS | 94 |
| 2 | NAUSEA | 94 |
| 3 | FATIGUE | 92 |
| 4 | PAIN | 90 |
| 6 | HEADACHE | 72 |
| 7 | ANXIETY | 66 |
| 8 | CHRONIC KIDNEY DISEASE | 56 |
| 9 | DIARRHOEA | 53 |
| 10 | SOMNOLENCE | 51 |
| 11 | DYSPNOEA | 47 |
| 12 | WEIGHT DECREASED | 46 |
| 13 | FALL | 45 |
| 14 | BACK PAIN | 44 |
| 15 | COMPLETED SUICIDE | 43 |
| 16 | DEPRESSION | 43 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
If you are intolerant to chlorzoxazone, you should not take this medicine.
Known Drug Interactions
Examples: Strong CYP3A inhibitors: itraconazole, clarithromycin Moderate CYP3A inhibitors: fluconazole, verapamil Weak CYP3A inhibitors: chlorzoxazone, ranitidine Strong and Moderate CYP3A Inducers Clinical Impact: Concomitant use with a strong or moderate CYP3A inducer decreases lemborexant exposure, which may reduce DAYVIGO efficacy [see Clinical Pharmacology ( 12.3 )].
Mechanism: Chlorzoxazone slows down the process your body uses to get rid of lemborexant. This may lead to higher levels of the sleep medicine in your blood.
What to do: Your doctor may need to monitor you more closely for extra sleepiness or adjust your dose.
This is a plain-language summary of interactions documented in FDA labeling, not individualized advice. Ask a pharmacist or prescriber before combining medications.
Common Questions
Can this medicine make me sleepy?
How often should I take this medicine?
What should I do if I have side effects?
Can I take this with other medicines?
How long does it take for this medicine to work?
Can I drive while taking this medicine?
What does the tablet look like?
How should I store this medicine?
What if the regular dose doesn't work?
Can this medicine cause allergic reactions?
What are the common side effects of chlorzoxazone?
Does chlorzoxazone interact with other medications?
What drug class is chlorzoxazone?
Is chlorzoxazone safe during pregnancy?
Related Medications in Muscle Relaxant
Other drugs grouped near chlorzoxazone - same-class peers and common alternatives.
baclofen
Lioresal, Gablofen
Baclofen is a muscle relaxant.
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botulinum toxin A
Botox
Botox is a drug that blocks nerve signals to muscles.
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carisoprodol
Soma
Carisoprodol is a muscle relaxant.
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cyclobenzaprine
Flexeril, Amrix
Cyclobenzaprine is a muscle relaxant.
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dantrolene
Dantrium
Dantrolene is a muscle relaxant.
Compare with chlorzoxazone →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for chlorzoxazone
The FDA label for chlorzoxazone (sold under brand names such as Parafon Forte) classifies it as a prescription-only medication in the Muscle Relaxant class. This medicine treats discomfort from muscle problems. Official labeling lists 5 commonly reported side effects, including Drowsiness, Dizziness, Lightheadedness.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 1,256 voluntary reports. The database also lists 1 documented drug interaction derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.19.
Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice, always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: March 1, 2025
Read our methodology - how this data is sourced, computed, and verified.
Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled and last refreshed May 2026. See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a correction.
All federal data sources used on this page
- FDA Orange Book - approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed - NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) - post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm - standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files - federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database - current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages