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Can Cannabis Reduce HIV Disease Progression?


THC, the main psychoactive component in marijuana, was associated with decreased viral load and lower risk of death in monkeys infected with a virus related to HIV.

Cannabis has been shown in studies to improve appetite, relieve chronic pain, and reduce nausea due to chemotherapy. Many people with HIV/AIDS use medical marijuana to combat wasting and other symptoms, which raises questions about what effects it might have on HIV and its progression.

Many immune cells express cannabinoid receptors, indicating that cannabis may influence immune function. Some prior research suggested that marijuana use is associated with HIV disease progression, but such studies were prone to confounding by socioeconomic and other factors related to illegal drug use.

As described in the June 2011, issue of AIDS Research and Human Retroviruses, Patricia Molina and colleagues from Louisiana State University Health Sciences Center examined the impact of ongoing administration of delta-9-tetrahydrocannabinol (THC) in macaque monkeys exposed to simian immunodeficiency virus (SIV).

Eight rhesus macaques received twice-daily intramuscular injections of either THC or a placebo. After 28 days, they were intravenously inoculated with a highly infectious dose of SIV. The researchers looked and immune and metabolic indicators of disease progression during the initial 6-month asymptomatic phase after infection.


  • THC administration did not significantly increase viral load or exacerbate immune dysfunction.
  • After exposure to SIV, the monkeys showed measurable viral loads, decreased CD4/CD8 T-cell ratios, and increased CD8 cell proliferation.
  • Administration of cannabis prior to infection produced little or no effects on these parameters.
  • THC-treated monkeys lost CD4 cells more slowly than the placebo group.
  • Monkeys given THC had a significantly lower early mortality rate compared with placebo-treated animals.
  • THC-treated monkeys had lower plasma and cerebrospinal fluid SIV viral load than those in the placebo group.
  • Monkeys in the THC group also experienced less wasting, though the difference did not reach statistical significance.
  • In a laboratory study, THC decreased SIV replication in MT4-R5 cells in vitro.

"These results indicate that chronic [THC] does not increase viral load or aggravate morbidity and may actually ameliorate SIV disease progression," the study authors concluded.

"Two of the [placebo-treated] animals succumbed to SIV infection shortly after 5 months, and a third reached end stage at 7 months," they elaborated in their discussion. "Among the [THC-treated] animals, the first animal did not reach end stage until 11 months post-SIV inoculation. "

"We speculate that reduced levels of SIV, retention of body mass, and attenuation of inflammation are likely mechanisms for [THC]-mediated modulation of disease progression that warrant further study," they wrote.

Investigator affiliations: Departments of Physiology, Pharmacology, Medicine, Microbiology, and Pathology, Louisiana State University Health Sciences Center, New Orleans, LA; and School of Public Health, Alcohol Research Center, and Alcohol and Drug Abuse Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA.


PE Molina, P Winsauer, P Zhang, et al. Cannabinoid Administration Attenuates the Progression of Simian Immunodeficiency Virus. AIDS Research and Human Retroviruses 27(6): 585-592 (free full text). June 2011.