The short answer
DIM might change how quickly your body clears ropinirole, but a clinically important interaction has not been demonstrated. Review a planned DIM supplement with your prescriber rather than changing your ropinirole dose yourself.
What this answer covers
Oral 3,3′-diindolylmethane supplements, especially the absorption-enhanced formulation studied in small trials; I3C and ordinary vegetable intake are separate exposures.
- Supplement or preparation
- 3,3'-Diindolylmethane
- Medication ingredient
- ropinirole
Why an interaction is considered
Ropinirole is mainly cleared through the liver enzyme CYP1A2. A small human DIM study reported increased activity of that enzyme after four weeks. This makes an effect on ropinirole plausible, but the study did not give participants ropinirole.
How strong is the evidence
The repeated-dose human result is reported in a conference abstract, with limited methods and uncertainty estimates. Laboratory experiments also found different effects on enzyme production and immediate enzyme activity. These results do not establish a reliable change in your medication level.
Check which supplement you have
The human studies used an absorption-enhanced DIM formulation. Another study measured how that product entered the bloodstream after a single dose. Results cannot be assumed identical for every DIM supplement, and they should not be automatically transferred from indole-3-carbinol or vegetables.
How to handle a planned change
Tell your pharmacist or prescriber before starting or stopping the supplement, and bring the product label. Report a clear change in symptom control or side effects. These sources do not establish a protective spacing interval or a standard ropinirole dose adjustment for this supplement.
Evidence and practical considerations
Absorption & effectiveness
DIM has human enzyme-probe and laboratory signals relevant to CYP1A2, but reduced ropinirole levels or effectiveness has not been demonstrated.
- Exact scope
- Oral 3,3′-diindolylmethane supplements, especially the absorption-enhanced formulation studied in small trials; I3C and ordinary vegetable intake are separate exposures. with Oral immediate-release ropinirole; hydrochloride salt expressed as equivalent free base in the inspected label.
- Medication form and route
- oral ropinirole; supplement preparation and route described in scope
- Timing or duration
- No exact-pair safe duration or protective spacing interval established.
What remains uncertain
- Small conference-abstract enzyme study and laboratory work do not measure ropinirole; formulation and endpoint differences prevent quantitative prediction.
Read the supporting source summaries
Source 1: current product label
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: People prescribed oral immediate-release ropinirole tablets for Parkinson disease or primary restless legs syndrome.
Ropinirole can cause somnolence, sudden sleep episodes and orthostatic hypotension. Concomitant sedating medicines or alcohol can increase sleepiness risk. CYP1A2 is its major metabolic enzyme; inhibitors and inducers may alter clearance. Ciprofloxacin increased exposure, whereas theophylline did not. Cigarette smokers had lower dose-normalized exposure than nonsmokers in a small RLS comparison.
How this applies: Exact oral ropinirole risk and metabolic context; section 11 justifies hydrochloride-to-free-base active-moiety identity only.
None of these ten supplement pairs is directly tested in this label. Cigarette smoking is not interchangeable with oral cannabis or isolated CBD; ciprofloxacin results are not caffeine results. No extended-release kinetic equivalence assumed.
Source 2: original conference abstract, publisher-deposited metadata
doi.org · Source check Sep 10, 2026
Population: 14 healthy adults, eight in lower-dose and six in higher-dose group.
Reported mean CYP1A2 activity increased by 250% and 181% in the respective groups. DIM systemic exposure fell with repeated dosing. No significant adverse effects were reported.
How this applies: Direct DIM human surrogate evidence, indirect to ropinirole; distinct from I3C and food consumption.
Conference abstract, not a full report; no ropinirole exposure or clinical outcome. Cannot transfer numerical enzyme changes to drug levels. CYP assay detail and uncertainty estimates limited.
Source 3: human hepatocyte and enzyme experiment
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Cultured primary human hepatocytes and enzyme assays, not treated patients.
DIM increased CYP1A2 gene expression, while direct enzyme assays also showed inhibition; the net effect depended on experimental conditions.
How this applies: Mechanistic context only, not proof of increased clearance or reduced ropinirole effectiveness.
No ropinirole or clinical oral dosing; gene expression and acute enzyme inhibition are different endpoints.
Source 4: single-dose randomized phase 1 pharmacokinetic study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Drug-free nonsmoking healthy adults in small dose cohorts.
Measured DIM exposure and short-term tolerability. Exposure was formulation- and dose-dependent; single doses up to 200 mg produced no reported related adverse effects.
How this applies: Separates direct DIM pharmacokinetics from I3C evidence and from a medication interaction.
Did not test ropinirole or establish chronic enzyme effects. This specialized formulation cannot define the exposure from every DIM product.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Sources inspected and exact current claim adjudicated; no clinical review asserted. | |
| Research summary published |
Article revision: 7297f8723d5de6ed
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.