Ask Dr. David: What Are Some of the Known Side Effects of Cannabis?

Aug 30, 2018

In recent years I have been fortunate to work with a wide range of patients who have benefited greatly from medical cannabis. One of the primary purposes of this blog series is to educate our community, so I decided to use this post to address some of the concerns associated with cannabis use so people can be fully informed when deciding if medical cannabis is right for them or a loved one.

Until more research can be done on the effects of cannabis, I find it best to rely on the patient’s specific feedback when assessing negative side effects. Compared to most of the other medications patients use, I have received very few complaints about negative effects from medical cannabis. I have also observed that people often report unexpected “positive side-effects,” where some other aspect of their health is improved even though it may not have been one of the debilitating symptoms that led the patient to see me in the first place.

Although most of the more significant reported negative effects of cannabis have been attributed to THC, I have had two patients (out of hundreds) react poorly to CBD even at very small doses. However, they were better the next day, which is what I would expect. This is almost always the case with THC as well.


Probably the most concerning side effect reported from cannabis use is the triggering or exacerbating of psychosis/schizophrenia. Although Wholistic ReLeaf has not had a single report of this side effect in any of the more than 800 patients we have certified, it is important that people are made aware of this potential side effect. Early symptoms of psychosis include, but are not limited to:

  • Difficulty thinking clearly or concentrating
  • Development of suspicion or discomfort with other people
  • A decline in hygiene
  • Self-isolation
  • Loss of emotion
  • Development of strong/inappropriate emotion
  • A decline in work or school performance

More advanced symptoms include, but are not limited to:

  • Delusions
  • Hallucinations
  • Hearing voices
  • Insomnia
  • Anxiety
  • Agitation

Because these symptoms may not be apparent to the patient, family members and friends should be on the lookout for them. If there are concerns regarding the development or escalation of these symptoms, the patient should immediately stop using medical cannabis, and their doctor should be notified.

Memory and Cognitive Function

Deficiencies in memory and cognitive function resulting from cannabis use seem to be more of a problem in children and young adults. This seems less of a problem once the brain has fully developed by age 22. A recent study indicated that while these issues are real, they may not be long-lasting. Young people who heavily used cannabis scored lower in learning ability, ability to abstract, processing speed, memory, and attention, compared to non-users. However, they also found these side effects significantly improved 72 hours after the cessation of cannabis use.

Intestinal Symptoms

While cannabis is quite effective in reducing symptoms of colitis, including persistent diarrhea, it also has the potential to push a patient past “normal” stool passage into constipation. This appears to be more common when cannabis is swallowed (e.g., pills, oils, edibles), as opposed to when cannabis is ingested via other routes of administration, such as inhalation, transdermal, or nasal.

Making An Informed Decision

As with everything we do, it is essential to weigh the possible or obtained benefits against the potential risks or adverse side effects. We must consider the pros and cons when comparing medical cannabis to other treatment alternatives. Each patient responds differently to various treatments, including their unique tolerance for potential side effects. As a result, it is crucial that patients and their loved ones be well-informed when choosing a treatment plan.

About Wholistic ReLeaf

Wholistic ReLeaf, founded in 2016 by Dr. David Berger of Wholistic Pediatric and Family Care, empowers families and patients to choose the best treatment approach available for their medical condition. The mission of Wholistic ReLeaf is to evaluate and certify qualified patients who meet the State of Florida legal requirements for receiving medical cannabis, and provide medical cannabis management and dosing consultations to patients certified by other Florida physicians. Wholistic ReLeaf is committed to providing patients with the best possible care, while also complying with the ever-shifting legal landscape of medical cannabis in the State of Florida.

For more information, or to find out if you or a patient you know may be eligible to use medical cannabis as part of a customized treatment plan, visit


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