The short answer
Alfalfa has not been shown to increase chlorpromazine-related photosensitivity in people. The original alfalfa evidence concerns animal feed, while chlorpromazine’s own sun-sensitivity precaution still applies.
What this answer covers
Oral chlorpromazine with the exact supplement preparation described.
- Supplement or preparation
- Medicago sativa
- Medication ingredient
- chlorpromazine
The alfalfa study involved horses
Investigators examined skin outbreaks in horses eating alfalfa hay. Two of three horses in a small feeding experiment developed compatible lesions. This was a substantial feed exposure, not people taking an alfalfa capsule with chlorpromazine.
The suspected cause was not confirmed
Analyses did not establish the proposed chlorophyll or pheophorbide explanation in the implicated samples. The uncertainty should remain visible rather than assigning every alfalfa preparation a known phototoxic dose.
Chlorpromazine has an independent precaution
Its label describes photosensitivity and advises avoiding undue sun exposure. This applies even when no supplement interaction has been confirmed; the animal study cannot quantify how much, if at all, alfalfa adds to that risk.
Check the preparation if you develop a reaction
Discuss the actual plant part, preparation and other medicines with your pharmacist. Follow chlorpromazine’s sun precautions and seek advice for a new significant skin reaction. No hours-apart schedule has been validated for this combination.
Evidence and practical considerations
Side effects & toxicity
Alfalfa has not been shown to increase chlorpromazine-related photosensitivity in people. The original alfalfa evidence concerns animal feed, while chlorpromazine’s own sun-sensitivity precaution still applies.
- 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
- Alfalfa-hay horse outbreaks and small feeding experiment do not establish human supplement co-use, causal phototoxin or a chlorpromazine interaction.
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 study
pubmed.ncbi.nlm.nih.gov · Source check Sep 10, 2026
Population: Horses involved in alfalfa-hay-associated skin outbreaks, including a three-horse feeding experiment.
Two experimentally fed horses developed compatible lesions. The investigators did not confirm suspected chlorophyll or pheophorbide causes in implicated samples.
How this applies: Animal observation does not establish human exact-pair photosensitivity.
Not people taking chlorpromazine; hay exposure differs from supplements and the photosensitizing cause remained unresolved.
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: 2ed6c0449968b90f
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.