Last updated on: 5/30/2008 | Author:

Is Marijuana Bad for the Immune System?

PRO (yes)


Donald P. Tashkin, MD, in his 2001 article “Effects of Smoked Marijuana on the Lung and Its Immune Defenses: Implications for Medicinal Use in HIV-Infected Patients,” published in the Journal of Cannabis Therapeutics, stated:

“Frequent marijuana use can cause airway injury, lung inflammation and impaired pulmonary defense against infection. The major potential pulmonary consequences of habitual marijuana use of particular relevance to patients with AIDS is superimposed pulmonary infection, which could be life threatening in the seriously immunocompromised patient.

In view of the immunosuppressive effect of THC, the possibility that regular marijuana use could enhance progression of HIV infection itself needs to be considered, although this possibility remains unexplored to date.”



Gabriel Nahas, MD, PhD, Professor Emeritus at Columbia University, wrote in an editorial published Mar. 1997 in the Wall Street Journal:

“This smoke [marijuana] contains carbon monoxide, acetaldehyde, napthalene and carcinogens. Inhalation of THC decreases lung defense mechanisms which are already compromised in AIDS patients, who are extremely vulnerable to pulmonary infections and tumors like Kaposi’s Sarcoma.

Thus marihuana smoke is a questionable choice to treat the symptoms of AIDS or cancer, especially when safer and more effective medications are available.”

Mar. 1997


The US DEA wrote the following to in a Jan. 2, 2002 email:

“[M]arijuana can affect the immune system by impairing the ability of T-cells to fight off infections, demonstrating that marijuana can do more harm than good in people with already compromised immune systems.

Because of these immune suppression properties, the National Institutes of Health recommends that people with HIV, and others whose immune systems are impaired, should avoid marijuana use.”

Jan. 2, 2002

CON (no)


The Annals of Internal Medicine, stated in its Aug. 19, 2003 article titled “Short-Term Effects of Cannabinoide in Patients with HIV-1 Infection”:

Conclusions: Smoked and oral cannabinoids [marijuana] did not seem to be unsafe in people with HIV infection with respect to HIV RNA levels, CD4 and CD8 cell counts, or protease inhibitor levels over a 21-day treatment.”

The accompanying “Summaries For Patients” provided by the journal stated:

“Patients receiving cannabinoids [smoked marijuana and marijuana pills] had improved immune function compared with those receiving placebo. They also gained about 4 pounds more on average than those patients receiving placebo.”

Aug. 19, 2003


Lynn Zimmer, PhD, wrote in her 1997 book Marijuana Myths, Marijuana Facts: A Review of the Scientific Evidence:

“There is no evidence that marijuana users are more susceptible to infections than non-users.

Early studies that showed decreased immune function in cells taken from marijuana users have since been disproven.

Indeed, not a single case of marijuana-induced immune impairment has ever been observed in humans.”



GW Pharmaceuticals stated the following on its website (accessed Jan. 2004):

“AIDS (Acquired Immune Deficiency Syndrome) wasting syndrome was a very frequent complication of HIV infection prior to the advent of protease-inhibitor drugs, and has been associated with major weight loss and cachexia, serving to further debilitate its victims, already weakened by immune system failure and opportunistic infections.

Cannabis has been a frequently employed alternative medicine for the condition, particularly in the USA, because of its reported benefits on appetite and amelioration of other AIDS symptoms.”

Jan. 2004