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.
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
- Dizziness
Dizziness
94 reports
- Nausea
Nausea
94 reports
- Fatigue
Fatigue
92 reports
- Pain
Pain
90 reports
- Headache
Headache
72 reports
- Anxiety
Anxiety
66 reports
- Chronic Kidney Disease
Chronic Kidney Disease
56 reports
- Diarrhoea
Diarrhoea
53 reports
- Somnolence
Somnolence
51 reports
- Dyspnoea
Dyspnoea
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) 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.
This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.
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?
What pregnancy or breastfeeding source fields are listed for chlorzoxazone?
Related Medications in Muscle Relaxant
Other drugs grouped near chlorzoxazone - same-class peers and common alternatives.
baclofen
Lioresal, Gablofen
Baclofen is a muscle relaxant.
Compare with chlorzoxazone →
botulinum toxin A
Botox
Botox is a drug that blocks nerve signals to muscles.
Compare with chlorzoxazone →
carisoprodol
Soma
Carisoprodol is a muscle relaxant.
Compare with chlorzoxazone →
cyclobenzaprine
Flexeril, Amrix
Cyclobenzaprine is a muscle relaxant.
Compare with chlorzoxazone →
dantrolene
Dantrium
Dantrolene is a muscle relaxant.
Compare with chlorzoxazone →
Compare beyond drug class
Nationwide peers by FAERS volume & death-report share
Two PlainMeds-derived comparison paths for chlorzoxazone: nearest FDA FAERS report volume and nearest death-report share among drugs with at least 1,000 logged reports, excluding same-class neighbors listed above. Counts reflect reporting volume, not proven individual harm.
Similar FAERS report volume
Nearest drugs by total FAERS reports. This record: 1,256.
Similar death-report share
Nearest drugs by FAERS death-report share. This record: 10.35%.
- sotalol Δ 0.02 pts · 16,062 reports · Class III Antiarrhythmic / Beta-Blocker 10.37%death share
- nisoldipine Δ 0.02 pts · 1,191 reports · Calcium Channel Blocker 10.33%death share
- prednisone Δ 0.02 pts · 482,856 reports · Corticosteroid 10.37%death share
- labetalol Δ 0.03 pts · 12,726 reports · Alpha/Beta-Blocker 10.33%death share
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
FDA bioequivalence and label-record context for narrow therapeutic index medicines
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
Save on chlorzoxazone
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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 are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.
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. This registry does not provide medication decisions.
Last updated: March 1, 2025
PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.
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 from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.
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