Diphenidine proposed for Schedule I — proposed, not scheduled

Diphenidine, a dissociative hallucinogen, is not yet a federally controlled substance in the United States — though DEA proposed placing it in Schedule I on May 26, 2026.

The Drug Enforcement Administration published a proposed rule on May 26, 2026, seeking to place it in Schedule I of the Controlled Substances Act. [1]

Nothing about handling diphenidine is illegal under this docket right now. A proposed rule proposes; it does not schedule anything on its own. [1] If the DEA finalizes it, the rule would apply the full range of Schedule I controls — regulatory restrictions plus administrative, civil, and criminal penalties — to anyone who manufactures, distributes, possesses, or otherwise handles diphenidine. [1] Until a final rule publishes with its own effective date, that has not happened.

Diphenidine has no approved medical use in the United States and a high potential for abuse. [1] It belongs to the 1,2-diarylethylamine class of dissociatives. [1] Diphenidine has been encountered in 11 states, and at least five fatalities have been associated with its use. [1] Anecdotal reports suggest onset of action between 10 and 30 minutes and duration generally between 2.5 and 6 hours. Treat these figures as rough and unverified, not something to plan a dose around. [1] Internationally, the UN Commission on Narcotic Drugs voted in April 2021 to place diphenidine in Schedule II of the 1971 Convention on Psychotropic Substances. [1]

Procedurally, this is a proposed rule, not a temporary or final scheduling action. The public comment period closes June 25, 2026, and anyone wanting a hearing on the proposal must request one by the same date. [1]

For anyone using diphenidine now: it remains under whatever legal status it currently has, unchanged by this proposal.

References

1. Schedules of Controlled Substances: Placement of Diphenidine in Schedule I — Federal Register