How Drugs of Abuse Including Cannabis Affect the Immune System and Infection Risk | Research

The takeaway

A review found that marijuana, opiates, cocaine, nicotine, and alcohol all suppressed immune function through receptor-mediated mechanisms, increasing susceptibility to infections including in the context of HIV/AIDS.

Read this if you want to understand how cannabis affects the immune system and infection risk.

Cannabis immunosuppression is receptor-mediated, occurring on immune cells and in the nervous system

What the researchers found

The review described how multiple drugs of abuse, including marijuana, modulated the immune system. For marijuana and opiates, immunosuppressive effects were receptor-mediated, occurring both directly through receptors on immune cells and indirectly through receptors in the nervous system. Cocaine and nicotine showed similar receptor-mediated immunomodulatory effects.

The immunosuppressive properties of these drugs increased susceptibility to opportunistic infections, which became an urgent public health concern with the AIDS epidemic. The review noted a long-recognized relationship between drug abuse and increased infection levels, with mechanistic research providing explanations for this clinical observation.

Why it matters

Understanding how cannabis affects the immune system has dual significance: it explains increased infection susceptibility in cannabis users and points toward potential therapeutic applications of cannabinoid immunomodulation in autoimmune and inflammatory conditions. The receptor-mediated nature of these effects suggested they could potentially be targeted pharmacologically.

The numbers in context

No specific quantitative data were presented in the abstract.

How the study worked

This was a narrative review covering the immunomodulatory mechanisms of marijuana, opiates, cocaine, nicotine, and alcohol, synthesizing evidence from basic science, immunology, and clinical observations of infection susceptibility.

What this study cannot tell us

The review covered five different drug classes broadly, limiting depth on cannabis specifically. Much of the evidence was from in vitro and animal studies. The clinical significance of cannabinoid immunosuppression in otherwise healthy users remained unclear.

How to read the evidence

This is a narrative review synthesizing immunological and pharmacological evidence across multiple drugs, providing moderate-level evidence.

When this study was published

Published in 2003. Subsequent research has refined understanding of cannabinoid immunomodulation and explored therapeutic applications.

The bigger picture

The immunomodulatory properties of cannabinoids have since been investigated for therapeutic applications in autoimmune diseases and inflammatory conditions. The finding that CB2 receptors on immune cells mediate many of these effects has led to research on CB2-selective drugs that could modulate immunity without psychoactive effects.

Questions still open

Does cannabis immunosuppression translate to clinically meaningful increases in infection risk for typical users? Can the immunomodulatory properties of cannabinoids be harnessed for treating autoimmune conditions?

Common questions

Does cannabis weaken the immune system?

This review found that cannabis has immunosuppressive effects mediated through cannabinoid receptors on immune cells. Whether this translates to clinically meaningful infection risk for typical users is less clear, but the effect is documented in both laboratory and animal studies.

Could cannabis immune effects be used therapeutically?

The immunosuppressive properties of cannabinoids have been investigated for potential use in autoimmune and inflammatory conditions, where dampening the immune response would be beneficial. CB2-selective compounds are being explored for this purpose.

Read the original research

Microbial infections, immunomodulation, and drugs of abuse.

Clinical microbiology reviews, 16(2), 209-19

View on PubMed ↗

Citation

Friedman, Herman; Newton, Catherine; Klein, Thomas W. (2003). Microbial infections, immunomodulation, and drugs of abuse.. Clinical microbiology reviews, 16(2), 209-19.