THC Worked as an Anti-Nausea Drug for Cancer Chemotherapy Patients in a Landmark 1975 Trial | Research

The takeaway

Oral THC prevented vomiting in 12 of 15 chemotherapy courses compared to zero of 14 placebo courses, and no patient vomited while experiencing a subjective high.

Read this if you want to understand the clinical evidence behind using THC for chemotherapy-related nausea and vomiting.

80% vs. 0%
THC prevented vomiting in 12/15 courses; placebo prevented it in 0/14

What the researchers found

In a double-blind, randomized, placebo-controlled trial, oral THC was tested as an anti-nausea treatment for cancer patients receiving chemotherapy drugs known to cause severe vomiting. The results were stark: THC produced an antiemetic effect in 14 of 20 total courses (and 12 of 15 courses in patients who completed the study). Placebo produced zero antiemetic responses in 22 courses.

A notable observation: no patient vomited while experiencing a subjective high from THC. The study was published in the New England Journal of Medicine, lending significant credibility to cannabis as a potential chemotherapy support medication.

Why it matters

Published in the New England Journal of Medicine in 1975, this was one of the first rigorous clinical trials demonstrating that THC has genuine antiemetic properties. It helped launch the medical marijuana movement for chemotherapy support and eventually contributed to the development of synthetic THC drugs like dronabinol (Marinol) for this indication.

The numbers in context

- 22 patients enrolled, 20 evaluable

- THC antiemetic effect: 14 of 20 courses (70%)

- Completers: 12 of 15 THC courses (80%) vs. 0 of 14 placebo courses (0%)

- P < 0.001

- Zero vomiting episodes during subjective high

How the study worked

Double-blind, randomized, placebo-controlled crossover trial. Twenty-two cancer patients receiving chemotherapy known to cause central nausea and vomiting were enrolled. Each patient served as their own control, receiving both oral THC and placebo in separate courses. Twenty patients were evaluable.

What this study cannot tell us

Small sample of 22 patients with only 20 evaluable. The abstract does not specify the THC dose. Crossover design means carryover effects are possible. Published in 1975, before modern antiemetic drugs (ondansetron, etc.) were available, so the comparator is placebo rather than current standard of care.

How to read the evidence

Randomized, double-blind, placebo-controlled crossover trial published in the New England Journal of Medicine. Small sample but rigorous design with highly significant results (P < 0.001).

When this study was published

Published in 1975 in the NEJM. One of the most cited early studies on medical cannabis. Led to FDA approval of synthetic THC for chemotherapy nausea a decade later.

The bigger picture

This trial in the New England Journal of Medicine was a watershed moment. It transformed the anecdotal observation that marijuana reduces nausea into clinical evidence. The FDA eventually approved synthetic THC (dronabinol) for chemotherapy-induced nausea in 1985, a direct descendant of research that began with studies like this one.

Questions still open

How does THC compare to modern antiemetic drugs like ondansetron for chemotherapy nausea?
Does the anti-nausea effect require the psychoactive high, or can it be separated?

Read the original research

Antiemetic effect of delta-9-tetrahydrocannabinol in patients receiving cancer chemotherapy.

The New England journal of medicine, 293(16), 795-7

View on PubMed ↗

Citation

Sallan, S E; Zinberg, N E; Frei, E. (1975). Antiemetic effect of delta-9-tetrahydrocannabinol in patients receiving cancer chemotherapy.. The New England journal of medicine, 293(16), 795-7.