Cannabis Health Benefits & Risks

Cannabis is one of the oldest plants cultivated by man, and has been used as a medicinal and recreational plant for thousands of years. With the growing (re)legalization of cannabis in many parts of the world, there has been renewed interest in the potential health benefits and risks associated with its use. In this article, we will explore the most well-researched health benefits and risks of cannabis, as well as some common drug-drug interactions to be aware of.

Benefits:

In 2017, the National Academies of Sciences, Engineering and Medicine published a very comprehensive 487 page review on “The health effects of cannabis and cannabinoids”, where they grouped the results from more than 10 000 studies based on their weight of evidence. Results from this review showed that there is conclusive / substantial evidence that cannabis / cannabinoids are effective for treating: 

• Chronic pain, especially pain related to neuropathy, cancer, rheumatoid arthritis, multiple sclerosis and musculoskeletal issues. Relief from chronic pain is by far the most common reason for why people use medical cannabis. In fact, many patients are replacing the use of conventional pain medications such as opioids with cannabis due to its efficacy, accessibility and reduced severity of side effects. 
• Chemotherapy-induced nausea & vomiting. Oral THC preparations such as Nabilone and Dronabinol have been available for the treatment of chemotherapy-induced nausea and vomiting for more than 30 years. These THC preparations have been found to be just as effective, and in many cases even more effective, compared to other commonly used antiemetics.
• Multiple sclerosis spasticity symptoms. Multiple sclerosis (MS) occurs when the body’s immune system mistakenly attacks the myelin sheath (a protective covering around nerve cells). The majority of people living with MS experience spasticity, which can manifest as involuntary muscle spasms, tightness, and pain. There is substantial evidence that oral cannabinoids are an effective treatment for improving patient-reported multiple sclerosis spasticity symptoms.

There is also moderate evidence that cannabis / cannabinoids are effective for improving:

• Sleep disturbances associated with obstructive sleep apnea, fibromyalgia, chronic pain and multiple sclerosis. The majority of studies showing improvements in sleep were performed using Nabiximols (an oral spray containing ± equal amounts of THC and CBD). 

For all other conditions, there is still limited or insufficient evidence. It is important to note, however, that the absence of evidence does not necessarily mean “absence of effectiveness”, it merely indicates that more good quality research is needed before any conclusions can be drawn.

Risks:

There is substantial evidence of a statistical association between cannabis use and:

• worse respiratory symptoms and more frequent chronic bronchitis episodes (in chronic users only). However, there is moderate evidence that the cessation of cannabis smoking leads to improvements in respiratory symptoms
• development of problem cannabis use, schizophrenia, psychosis or cognitive deficits when consumed during the neurodevelopmental period (before the age of 25 years). The risk increases with use frequency and THC potency
• lower birth weight in babies (when used by the mother during pregnancy) 
• increased risk of motor vehicle crashes (especially when combined with alcohol)

There is moderate evidence of a statistical association between regular cannabis use and:

• increased symptoms of mania and hypomania in individuals with bipolar disorders 
• increased incidence of social anxiety disorder and depressive disorders 
• increased incidence of suicidal ideation and suicide attempts among heavy users

Drug-drug interactions:

Cannabis has been shown to interact with various different drugs including alcohol, sedatives, analgesics, anxiolytics, antidepressants, antipsychotics, antibiotics, anticonvulsants, blood thinners, proton-pump inhibitors, antiretrovirals and chemotherapy drugs. This is because cannabinoids are metabolized by the same enzymes which are responsible for metabolizing various other drugs (eg. CYP3A4 which metabolizes about a quarter of all drugs). Co-use of cannabis with drugs that are metabolized by the same enzymes will increase the “traffic” through these enzymatic pathways, leading to dangerous drug buildups and increased side effects. This is especially relevant for people who are taking multiple drugs at the same time. If you are using any chronic medication, please consult your doctor before combining it with cannabis to avoid potentially harmful drug-drug interactions. In the meantime, you can visit drugs.com and type in the name(s) of your medication(s) to see if there are any known interactions with cannabis.

Summary:

For most people using cannabis, the benefits outweigh the risks. However, it is important to remember that each person is unique and will experience the effects of cannabis differently. In addition, cannabis is a complex plant composed of numerous active compounds, and effects will vary from strain to strain and between different product types (eg. full spectrum cannabis extract vs THC / CBD  isolate). 

To minimize the risks associated with cannabis:

• avoid using cannabis before the age of 25
• choose low-potency THC or balanced THC:CBD-ratio cannabis products
• avoid combusted cannabis inhalation and give preference to nonsmoking methods 
• avoid deep inhalation practices
• avoid high-frequency cannabis use
• avoid potentially harmful drug-drug interactions 
• abstain from cannabis-impaired driving