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When to Not Use Cannabis

Cannabis-based products are approved for use to help treat numerous medical conditions, from chronic pain syndromes to terminal illness, to glaucoma. However, the process determining which conditions are approved for the prescription of medical cannabis varies from state to state. These processes do not always correlate with medical literature. For example, some states approve conditions based on public petitions and forums. This approval process puts some of the medical decision-making in the hands of the public rather than in the hands of providers. It is important that patients and providers understand the evidence behind cannabis as it pertains to their own conditions, as the benefit to harm ratio differs by case. Cannabis can be prescribed for some conditions that lack data supporting its efficacy or worse, have some evidence that cannabis may cause more harm than good. I will briefly review two such conditions.


The term glaucoma refers to a group of diseases characterized by increased pressure inside of the eye. Glaucoma is typically discovered by accident during a routine eye exam or while evaluating a different condition. It affects the nerve that carries vision from the eye to the brain. Left untreated, glaucoma will result in vision loss and blindness. Glaucoma is an approved condition for the prescription of cannabis-based products in multiple states. However, it is important to compare cannabis and cannabis-based products to other available treatments to determine which treatment is most appropriate. In this regard, cannabis may not be the ideal treatment in most cases.

The standard goal of therapy for patients with glaucoma is to lower the pressure inside of the eye, which prevents progression of the disease and vision loss.  Hence, the optimal treatment is the one with the greatest effect and fewest side effects. Cannabis has been shown to lower intraocular pressure in multiple studies, which in theory would make it a good medication for the treatment of glaucoma to prevent disease progression. However, there are multiple other medical and surgical therapies that are both more effective and have fewer potential side effects, making cannabis a less-than-ideal monotherapy for glaucoma. Multiple prescription eye drops that lower intraocular pressure significantly more than cannabis, such as prostaglandin drops (ex: latanoprost) and beta-blocker drops (ex: timolol). Both are effective and have been the standard of care for years. And ff drops do not provide enough relief, there are laser and surgical options which very effectively lower intraocular pressure. These procedures are also very safe. As such, even though cannabis-based products do have an effect on glaucoma, it is important not to ignore the more effective therapies available.

Hepatitis C Virus

Hepatitis C (HCV) is currently the most common cause of chronic liver disease in the United States. It is also an approved condition in some states for the prescription of cannabis. Up to 85% of patients who develop an infection with HCV as an adult develop chronic hepatitis, a progressive inflammatory condition of the liver that leads to cirrhosis. Cirrhosis can be thought of as the end-stage of liver disease, in which the structure and functions of the liver are destroyed. Cirrhosis is associated with high rates of liver cancer and mortality. Fortunately, many effective cures have been discovered for the most common form of HCV. New drugs like Harvoni (sofosbuvir/ledipasvir) have >95% response rates in as little as 8 weeks. With proper evaluation and treatment, HCV is becoming less of a strain on the population than ever before. For this reason, it is important to understand the potential impact of cannabis on the liver and on hepatitis C if cannabis is to be prescribed and used safely.

Little research has been done examining the relationship between cannabis and HCV. The lack of research should make physicians hesitant to prescribe cannabis-based products for HCV, as there isn’t enough evidence to justify using cannabis as a treatment. Multiple studies have found that patients with HCV who use cannabis have more severe fibrosis, which in theory can lead to cirrhosis and terminal liver disease faster (not exactly the ideal outcome for a medication supposed to help). Modulation of cannabinoid receptors in animal models has supported this finding, as the inhibition of the CB1 receptor (the most common cannabinoid receptor currently found in the liver) results in a decreased fibrotic response. Overall, the research performed suggests the influence of cannabis on liver disease due to HCV is at best neutral, and potentially harmful. If HCV is to be considered an appropriate condition for the prescription of cannabis, more research needs to be done to demonstrate that there are some benefits outweighing the potential risks.


This article is meant to give examples of how a medical process can be influenced by non-medical decision makers. For glaucoma, cannabis certainly has positive effects, but patients should speak to their doctors before deciding on a treatment, rather than blindly opting for medical cannabis. In the case of glaucoma, research suggests cannabis is not the most effective treatment. As for HCV, not only has there been no significant data to show reason to use cannabis, but also available data suggests that cannabis may actually cause harm. Overall, it is important for patients and physicians to understand that regardless of the condition for which cannabis is being recommended. As research continues, these findings may change and recommendations along with it. The goal of all medical therapy is to provide the optimal benefit with the least amount of unwanted side effects.


Sun X, Xu CS, Chadha N, Chen A, Liu J. Marijuana for Glaucoma: A Recipe for Disaster or Treatment? Yale Journal of Biology and Medicine. 2015. 88: 265-9.

Hezode C, Roudot-Thoraval F, Ngyuen S, Grenard P, Julien B, Zafrani ES, Pawlostky JM, Dhumeaux D, Lotersztajn S, Mallat A. Daily Cannabis Smoking as a Risk Factor for Progression of Fibrosis in Chronic Hepatitis C. Hepatology. 2005. 42(1): 63-71.

By |2019-04-18T19:49:51+00:00March 18th, 2019|Editorials, Health & Wellness, Marijuana|0 Comments

About the Author:

Dr. Bressman attended Swarthmore College, where he received a bachelors degree with a focus on biology, before attending the NYU School of Medicine, currently ranked as the #3 medical school by the US News Rankings. He is currently a resident in Internal Medicine at Montefiore Medical Center in the Bronx, NY. Dr. Bressman has participated in both basic science research, as well as clinical research, with multiple publications and awards. Most recently he was named the winner of the Trainee Award at the national conference for Society of Hospitalist Medicine for a rare case involving licorice toxicity. When not hard at work, Dr. Bressman can usually be found on the golf course or cooking at home.

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