Cannabis Chemovar Profiles May Be Linked to Different Symptom Relief and Side Effects
A 2023 proof-of-concept study found that cannabis flower products with different combinations of cannabinoids and terpenes were associated with different levels of symptom relief and side effects. The researchers’ study in the Journal of Cannabis Research introduced the Vigil Index of Cannabis Chemovars, a coding system intended to describe cannabis products by their measurable chemical profiles rather than by commercial strain names.
How the study was conducted
The research team analyzed de-identified data from the Releaf App, a mobile application that allows users to record cannabis products, consumption details, symptoms, symptom intensity and side effects in real time. The dataset covered sessions recorded between September 10, 2016, and March 11, 2021.
The final analysis included 204 users, 6,309 cannabis administration sessions and 633 distinct flower products with labeled cannabinoid and terpene information. The researchers identified 478 different chemovar codes in the dataset.
Because the data were collected retrospectively from app users, the study did not randomly assign people to products or include a placebo control. The results therefore show associations between product chemistry and reported experiences, not proof that a particular chemical profile caused a specific medical outcome.
What the Vigil Index measures
The Vigil Index summarizes four features of a cannabis flower product:
- the product’s most concentrated terpene;
- its second-most concentrated terpene;
- its THC potency range; and
- its CBD potency range.
Terpenes were assigned letter codes and grouped into concentration ranges. THC and CBD were represented by numbers corresponding to potency bands. For example, the code MC61 indicated myrcene and beta-caryophyllene as the two leading terpenes, THC in the 20%–24.9% range and CBD in the 0.01%–0.9% range.
The approach was designed to address a longstanding problem with cannabis labeling: commercial strain names do not reliably describe a product’s chemical composition. Products sold under similar names can have different cannabinoid and terpene profiles, while products with different names may share similar chemistry. The University of New Mexico’s overview of the project describes the index as an effort to make product comparisons more chemically meaningful.
Differences among the most frequently used chemovars
The researchers compared the five most frequently represented chemovars, adjusting the analyses for baseline symptom severity and total terpene content. They examined the full sample and two condition-specific groups: sessions aimed at treating pain, and sessions aimed at treating anxiety or depression.
Symptom-relief scores differed significantly among the chemovars in the overall sample, the pain group and the anxiety-or-depression group. Products containing somewhat higher levels of myrcene or terpinolene—roughly 0.50% to 1.0%—and no detectable CBD were generally associated with greater reported relief.
Two of the examples, M+A50 and T+L60, were associated with the strongest symptom-relief scores in the study’s robustness analysis. Both had no detectable CBD and contained somewhat higher concentrations of myrcene or terpinolene.
By contrast, the MC61 chemovar was associated with worsening anxiety or depression symptoms in that subgroup. Chemovars with detectable CBD, including MC61 and MC62, were generally associated with less symptom relief than the other examples.
Side effects also varied
The study found differences in reported positive, negative and context-specific effects across the five chemovars. Products with slightly higher myrcene or terpinolene levels and no detectable CBD were associated with more positive effects and fewer negative or context-specific effects.
Products represented by MC61 and MC62 were associated with two to three fewer positive effects than the other three chemovars. They were also linked to more negative and context-specific effects. Commonly reported negative effects in the broader dataset included dry mouth and red eyes, while feeling relaxed, feeling “chill,” feeling high and feeling tingly were among the most frequently reported positive or context-specific experiences.
Why the findings need cautious interpretation
The study does not establish that myrcene, terpinolene, CBD or any other single compound directly produced the observed differences. Users selected their own products, decided how much to consume and reported their own symptoms and side effects. People who use a particular product may differ from other users in their symptoms, expectations, prior cannabis experience or reasons for choosing that product.
The researchers also lacked important individual-level information, including participants’ ages, medical histories, other medications and detailed patterns of cannabis use. Terpene information was available for only a small portion of the original app sessions, and the analysis was limited to labeled product data. These factors restrict how widely the results can be generalized.
The study’s main contribution is therefore methodological. It shows that a standardized description based on cannabinoid and terpene content can reveal patterns that may be missed when products are compared only by strain name. The authors call for randomized studies that test specific chemovars under controlled conditions and examine how product chemistry interacts with individual patient characteristics.
For now, the Vigil Index should be viewed as a research and classification tool—not as a clinically validated guide for selecting cannabis to treat a medical condition. The U.S. Food and Drug Administration’s cannabis research guidance provides additional context on the distinction between studying cannabis-derived products and establishing that an unapproved product is safe and effective for a particular disease. General information about potential risks is also available from the Centers for Disease Control and Prevention.
