The short answer
A four-hour gap between riboflavin and chlorpromazine has not been validated by the original studies reviewed. Laboratory findings about vitamin metabolism and transport do not establish that timing rule.
What this answer covers
Oral chlorpromazine with the exact supplement preparation described.
- Supplement or preparation
- Riboflavin
- Medication ingredient
- chlorpromazine
Why riboflavin appears in interaction lists
Experiments found that chlorpromazine affected conversion of riboflavin into active flavin forms and altered flavin measurements in rats. These findings provide a plausible biological question, but not a clinical schedule.
The transport experiment was outside the human body
Another study used everted rat intestinal sacs and found inhibited riboflavin transport. It did not measure what happens when a patient takes ordinary oral doses together or four hours apart.
A mechanism cannot select an interval
Neither original experiment compared dosing gaps or showed that four hours restores vitamin status or chlorpromazine benefit in people. The interaction statement should therefore not present that number as proven.
Base supplementation on an actual need
Ask the pharmacist about the prescribed regimen and any nutritional concern rather than increasing riboflavin or changing chlorpromazine yourself. These experiments do not establish a routine need for high-dose vitamin B2.
Evidence and practical considerations
Timing & monitoring
A four-hour gap between riboflavin and chlorpromazine has not been validated by the original studies reviewed. Laboratory findings about vitamin metabolism and transport do not establish that timing rule.
- Exact scope
- Oral chlorpromazine with the exact supplement preparation described. with Oral chlorpromazine with the stated label and formulation limits.
- Medication form and route
- oral
What remains uncertain
- Original exact experimental evidence is rat tissue and intestinal transport. No measured human clinical benefit, deficiency incidence or tested four-hour rule; do not claim all human evidence absent.
Factors that may matter: Exact preparation and amount; Other medicines; Seizure history, alertness or electrolyte status where relevant.
Read the supporting source summaries
Source 1: Current U.S. regulatory product labeling
dailymed.nlm.nih.gov · Source check Sep 10, 2026
Population: Patients prescribed oral chlorpromazine.
May cause initial drowsiness, intensify other CNS depressants, lower the seizure threshold and cause photosensitivity. Has strong antiadrenergic and weaker peripheral anticholinergic effects.
How this applies: Exact ingredient and oral-route clinical context.
Label class warnings do not establish every exact botanical interaction, event rate or protective supplement interval.
Source 2: Original animal and laboratory study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Rats and rat tissue preparations.
Chlorpromazine inhibited conversion of riboflavin into active flavin forms and altered tissue or urinary flavins under experimental conditions.
How this applies: Direct experimental drug-nutrient evidence with clinical applicability limits.
Not a human dose-spacing or efficacy trial; no four-hour separation was validated.
Source 3: Original laboratory study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Everted rat intestinal sacs.
Chlorpromazine inhibited measured riboflavin transport in this experimental preparation.
How this applies: Supports a mechanism hypothesis, not an established clinical timing rule.
Ex vivo rat tissue, not patient absorption, nutrient deficiency incidence or a four-hour protective interval.
Research assessment: · Open full citations ↗
Review and change history
- Publication status
- Published research summary
- Clinical review
- Not yet recorded
| Date | Update |
|---|---|
| Article prepared | |
| Initial source-checked draft with exact preparation limits, original study findings and uncertainty. Clinical review not recorded. | |
| Research summary published |
Article revision: c2274c44170ccd30
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.