21 November 2019 

Montreal researchers explore cannabis use among people with HIV and hepatitis C

  • 80% of people with HIV used cannabis at least once weekly, mostly through smoking
  • The top reported reason was pleasure, followed by stress and anxiety management
  • Researchers found that cannabis use did not appear to affect HIV treatment adherence

In the first decade of the HIV pandemic, one complication was relentless weight loss (called wasting or the wasting syndrome). This complication could be caused by one or several factors, including changes in metabolism caused by HIV infection, chronic diarrhea, malabsorption and life-threatening infections and cancers. As the immune system deteriorated and people became weaker, loss of appetite and nausea became issues. In that era, some HIV-positive people smoked cannabis to increase their appetite and reduce nausea.

Today, severe weight loss caused by HIV is uncommon among people taking potent combination HIV treatment (ART) in Canada and other high-income countries. Even so, many HIV-positive people use cannabis. To find out more about cannabis use in the current era, a team of scientists at McGill University surveyed 104 people, some of whom had HIV and some who had both HIV and chronic hepatitis C virus infection (HCV).

The scientists found that cannabis use was common—nearly 80% of participants disclosed using it at least once weekly, usually via smoking. The most stated reason for cannabis use was for pleasure. A majority of participants disclosed that they used it to help manage issues such as anxiety, stress and chronic pain. People who used cannabis usually had good adherence to ART. The scientists found other interesting associations with cannabis use, which will be touched on later in this CATIE News bulletin.

Study details

The study team recruited 104 participants whose average profile was as follows:

  • age – 54 years
  • 90 men, 13 women and one transgender person
  • most participants were white (80%) and the other major ethno-racial groups were African, Caribbean and Black (6%) and Hispanic (6%)
  • chronic viral infections: HIV alone – 58%; HIV + HCV – 42%
  • CD4+ cell count – 600 cells/mm3
  • taking ART – 97%
  • had a detectable viral load – 12%
  • marital status: single – 84%; married/common law – 15%; widowed – 1%
  • common medical conditions: anxiety – 39%; depression – 33%; asthma – 27%; higher-than-normal blood pressure – 15%
  • many participants began using cannabis when they were 18 years old

Participants filled in a detailed survey under the supervision of a member of the research team. This supervision was solely to ensure that participants completed the survey.

Results—How did people use cannabis?

People used cannabis in the following ways:

  • smoked as a joint containing marijuana alone – 65%
  • smoked as a joint containing marijuana with tobacco – 45%
  • smoked in a pipe – 35%
  • smoked from a bong – 15%
  • used a vaporizer – 9%

Note that some people used it in more than one way.

About 34% of participants disclosed that they consumed cannabis as “edibles,” in brownies, cakes and cookies.

How often was cannabis used?

The frequency of cannabis use was as follows:

  • more than once daily – 32%
  • daily – 25%
  • weekly – 21%
  • monthly – 17%
  • rarely (two to three times per year) – 5%

About 67% of participants disclosed that they used cannabis in the 24 hours prior to their interview.

Reasons for use

Here are the main reasons participants stated that they used cannabis:

  • pleasure – 68%
  • to self-manage stress – 60%
  • to self-manage anxiety – 60%
  • to self-manage pain – 57%
  • social reasons – 40%
  • weight gain/appetite stimulation – 39% (people in this category used it mainly for appetite stimulation)
  • to enhance creativity during certain activities (work, hobbies, sex and relaxation) – 18%
  • other reasons (to improve mood/calm oneself when dealing with people and to concentrate better at work and while watching movies) – 17%


When participants were asked about the effectiveness of cannabis for self-management of conditions, responses varied. About 6% reported that it was not effective, while as many as 45% reported that it was “quite or extremely effective.”

Secondary effects

Apart from the intended use, some participants disclosed that they experienced the following when using or after using cannabis:

  • relaxation – 92%
  • feeling high – 74%
  • dry mouth – 64%
  • increased cough – 45%
  • increased shortness of breath – 27%
  • increased anxiety – 21%
  • paranoia – 22%

Note that some people may have experienced more than one secondary effect.

According to the scientists, most participants (68%) found these secondary effects “not bothersome at all.”

Bear in mind

Adherence to ART

The Montreal scientists found that 88% of cannabis users had an undetectable viral load (less than 50 copies/mL). This suggests that a very large majority of cannabis users did not have problems adhering to ART. These findings are in line with a recent study from Vancouver. In this study with 523 HIV-positive people, scientists found that cannabis had no impact on adherence to ART, even when the herb was used daily.

Inhaling smoke

Most participants in the Montreal study reported inhaling cannabis smoke. Nearly half of the participants noted that they had temporary increased respiratory symptoms limited to coughing and/or shortness of breath when inhaling cannabis smoke.

In reviewing the scientific literature on cannabis and any connection to serious respiratory illnesses, the Montreal scientists stated that cannabis smoking by itself is “not associated with increased risk of chronic obstructive pulmonary disease (COPD), lung function decline or lung cancer.” However, they added that “health care providers need to be aware of the potentially detrimental respiratory effects of smoking cannabis as joints and be ready to suggest alternative methods of drug delivery such as vaping. Consumption of cannabis as oils or edibles, particularly if [HIV-positive people] are also current or ex-cigarette smokers, is an alternative method of administration although one must be cognizant of the different pharmacokinetics of inhaled versus ingested cannabis, which may make such substitution of delivery method not preferable for the patient.”

Paranoia and anxiety

In the present study, 22% of participants disclosed that they had experienced paranoia and 21% experienced anxiety after using cannabis. The Montreal scientists stated:

“There is evidence that persons with a family history of schizophrenia and who have cannabis-induced psychosis should be strongly discouraged from using cannabis with high levels of psychoactive cannabinoids, most notably THC. Tools such as the Cannabis Use Disorder Identification Test-Revised (CUDIT-R) are designed to assist health care providers in identifying potentially hazardous cannabis use or a possible cannabis use disorder, for which further intervention may be required.”

Another team of scientists in Canada and other high-income countries have developed the “Lower-Risk Cannabis Use Guidelines.” The Montreal scientists stated that these guidelines are evidence based and “designed to reduce the risk of adverse public health outcomes from cannabis users…” They encouraged healthcare providers to familiarize themselves with the CUDIT-R as well as the lower-risk guidelines.

Alcohol, tobacco, anxiety and depression

The Montreal scientists stated that many (66%) of the participants also smoked tobacco. This proportion of people smoking tobacco is high; in contrast, estimates are that about 19% of HIV-negative Canadians smoke tobacco. In the Montreal study, there were relatively large proportions of participants who reported anxiety and depression. The scientists stated that “many participants in our study also reported alcohol use, suggesting that education regarding cannabis could be done in conjunction with counselling on tobacco and alcohol reduction/cessation strategies.”

Notes on this study

The Montreal study is imperfect. It was relatively small and done in one clinical centre, with a mostly male population. However, it is a good first step as it paves the way for future research with more people, including women and other key populations affected by HIV in Canada.

Some future research directions

In the present study, some participants disclosed that they used cannabis to relieve pain. The Montreal scientists also underscored the results from a different study which suggest that cannabis “could reduce the need for opioid analgesics for pain management…” They highlighted an analysis from Vancouver that suggests that some people use cannabis to reduce their dependency on crack-cocaine.

The Montreal scientists suggest that together, these findings “are relevant given the rates of mortality stemming from the opioid crisis in Canada.”


Lower-risk cannabis use guidelinesAmerican Journal of Public Health

Screening tools for problematic use of CannabisCanadian Public Health Association

Inflammation, HIV and marijuana  –  TreatmentUpdate 225

Alcohol, not marijuana, linked to liver injury in women with both HIV and hepatitis CCATIE News

Canadian survey compares marijuana use across different conditionsCATIE News

—Sean R. Hosein


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