Dose-response study of N,N-dimethyltryptamine in humans. I. Neuroendocrine, autonomic, and cardiovascular effects

This study (1994) was one of the first sanctioned studies using psychedelics following their classification as Schedule I substances. Participants received intravenous doses of DMT at 0.05,0.1,0.2, and 0.4 mg/kg. Neuroendocrine, autonomic, and cardiovascular effects were assessed. It was found that DMT can be safely administered to experienced hallucinogen users.


Background:  To begin applying basic neuropharmacological hypotheses of hallucinogenic drug actions to humans, we generated dose-response data for intravenously administered dimethyltryptamine fumarate’s (DMT) neuroendocrine, cardiovascular, autonomic, and subjective effects in a group of experienced hallucinogen users.

Methods:  Dimethyltryptamine, an endogenous mammalian hallucinogen and drug of abuse, was administered intravenously at 0.05,0.1,0.2, and 0.4 mg/kg to 11 experienced hallucinogen users, in a double-blind, saline placebo—controlled, randomized design. Treatments were separated by at least 1 week.

Results:  Peak DMT blood levels and subjective effects were seen within 2 minutes after drug administration, and were negligible at 30 minutes. Dimethyltryptamine dose dependently elevated blood pressure, heart rate, pupil diameter, and rectal temperature, in addition to elevating blood concentrations of β-endorphin, corticotropin, cortisol, and prolactin. Growth hormone blood levels rose equally in response to all doses of DMT, and melatonin levels were unaffected. Threshold doses for significant effects relative to placebo were also hallucinogenic (0.2 mg/kg and higher). Subjects with five or more exposures to 3,4-methylenedioxymethamphetamine demonstrated less robust pupil diameter effects than those with two or fewer exposures.

Conclusions:  Dimethyltryptamine can be administered safely to experienced hallucinogen users and dose-response data generated for several measures hypothesized under serotonergic modulatory control. Additional studies characterizing the specific mechanisms mediating DMT’s biological effects may prove useful in psychopharmacological investigations of drug-induced and endogenous alterations in brain function.”

Authors: Rick Strassman & Clifford Qualls

Become a psychedelic insider!

With a free Blossom membership you will always be in the know.

📰 Weekly newsletter about the psychedelic research

✔️ Unlimited access to our database and original articles

🖊️ Add (private) notes and comments to each page

Make an account

Study details

Compounds studied

Topics studied
Safety Healthy Subjects

Study characteristics
Placebo-Controlled Double-Blind

11 Humans


Authors associated with this publication with profiles on Blossom

Rick Strassman
Rick Strassman is an associate professor of psychiatry and best known for his DMT research in the late 1990s and his subsequent book DMT: The Spirit Molecule.

Inline Feedbacks
View all comments