The short answer
Some garlic preparations reduced a chlorzoxazone metabolism marker in small human studies. Those findings do not establish that garlic consistently increases chlorzoxazone blood levels or causes toxicity; the formulation and measured outcome matter.
What this answer covers
Allium sativum: repeated garlic oil and acute isolated diallyl sulphide studied; not equivalent to culinary garlic or every aged/powder extract.
- Supplement or preparation
- Allium sativum
- Medication ingredient
- chlorzoxazone
There is direct human probe evidence
Small studies gave chlorzoxazone as an enzyme probe before and after garlic oil or a garlic-derived constituent. The metabolite-to-parent ratio fell, which is consistent with reduced CYP2E1 activity.
A ratio is not a full blood-level measurement
The studies reported a metabolic ratio at selected times rather than demonstrating an increase in total chlorzoxazone exposure or improved absorption. Their results should not be converted into an exact dose adjustment or a measured toxicity rate.
Different garlic products may behave differently
The experiments used repeated garlic oil or acute diallyl sulphide. They do not establish the same effect from ordinary food amounts, aged garlic extract or every supplement. Chlorzoxazone’s own liver-injury warning does not prove that garlic makes that injury more likely.
Review the preparation and symptoms
Tell the prescriber which garlic product and dose you use. Do not change chlorzoxazone yourself or rely on a timing gap. Follow its label instructions about liver symptoms, including dark urine or jaundice, independently of whether garlic is involved.
Evidence and practical considerations
Absorption & effectiveness
Original human studies establish preparation-specific CYP2E1 probe-ratio inhibition, not a demonstrated increase in chlorzoxazone absorption/full exposure. Original broad blood-level claim insufficient as written; narrower metabolism finding retained.
- Exact scope
- Allium sativum: repeated garlic oil and acute isolated diallyl sulphide studied; not equivalent to culinary garlic or every aged/powder extract. with Oral chlorzoxazone tablets.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No unmeasured pair incidence, blanket class transfer or arbitrary spacing interval.
Factors that may matter: Preparation; Dose; Other medicines; Organ function.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed chlorzoxazone
Drowsiness and dizziness; additive CNS-depressant effects. Rare serious hepatotoxicity warning is intrinsic and not proof of supplement synergy.
How this applies: Exact chlorzoxazone RxCUI 2410 IN, with stated salt/formulation/route bridge.
No exact supplement-combination incidence or validated protective spacing; salt, route and release form limits apply.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy adults.
CYP2E1 phenotypic ratio decreased39%.
How this applies: Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy adults aged60–76years.
CYP2E1 phenotypic ratio decreased approximately22%.
How this applies: Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Source 4: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Eight volunteers in the diallyl sulphide comparison.
Ratio decreased, consistent with CYP2E1 inhibition.
How this applies: Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Research assessment: · Open full citations ↗
Absorption & effectiveness
Garlic oil or isolated diallyl sulphide reduced the measured hydroxychlorzoxazone/chlorzoxazone ratio in small human studies.
- Exact scope
- Studied garlic oil and isolated diallyl sulphide, not all garlic preparations. with Oral chlorzoxazone tablets.
- Medication form and route
- oral medication; oral supplement
What remains uncertain
- No exact-pair incidence or universally protective timing interval.
Factors that may matter: Preparation; Dose; Other medicines.
Read the supporting source summaries
Source 1: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy adults.
CYP2E1 phenotypic ratio decreased39%.
How this applies: Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Source 2: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: 12 healthy adults aged60–76years.
CYP2E1 phenotypic ratio decreased approximately22%.
How this applies: Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Source 3: original human study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Eight volunteers in the diallyl sulphide comparison.
Ratio decreased, consistent with CYP2E1 inhibition.
How this applies: Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Chlorzoxazone enzyme-probe phenotype, not a demonstrated full AUC increase, reduced absorption, clinical sedation or hepatotoxicity rate. Preparation-specific; garlic oil or isolated constituent is not all garlic food/extract.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Research summary published | |
| Article prepared | |
| Prepared exact chlorzoxazone article with formulation-specific evidence and uncertainty. |
Article revision: f619c14a9e9f4b1a
This guide brings together the evidence records used by our interaction checker. Each finding retains its own preparation limits, research date, and source summaries.
Full citations require verification. Reading this answer and the source summaries does not.
Taking other supplements or medications?
Use the checker to explore your other combinations. Ask a pharmacist to review the exact products, amounts and medical conditions in your complete list.
Open the interaction checkerInformation, not medical advice. Do not change prescribed treatment based on this guide.