From a medical point of view, there is no such thing as absolutely safe drinking, as studies have shown that even light drinking is harmful.
If my patient drinks daily, I advise him to reduce his alcohol consumption. If they are unable to reduce their alcohol consumption despite trying, I offer treatments to help them reduce or quit: Many people are surprised to learn that there are three FDA-approved drugs (naltrexone, acamprosate, and disulfiram) that can help with this , drinking less, and so on. Behavioral therapies—individual or group therapy—are similarly effective.
Regarding cannabis, I say to my patients that we are still not sure if there is a safe level of use, but that scientists believe frequent and higher THC use is riskier in general.
When my patients use cannabis, I ask them if they are using it for medical reasons and suggest alternatives that have more rigorous scientific backing. However, if you do plan to consume, I advise against smoking and vaping to protect your lungs, and I suggest using products with low concentrations of tetrahydrocannabinol (THC) or trying cannabidiol (CBD) instead.
THC and cannabidiol (CBD) are two of the active compounds in cannabis: THC, the psychoactive compound that makes people feel “high,” has been linked to more health risks. I suggest they try CBD edibles with less than 5 percent THC—with the caveat that edibles can enter the system more slowly and unpredictably, so patients should start low and go slow as they dose want to increase.
One reason we know less about the harms of cannabis compared to alcohol is that, until recently, the use of cannabis was illegal in many states. Now that the number of people using cannabis is increasing, we will better understand the potential risks by using studies comparing large groups of people who use cannabis and those who don’t over the course of time track time.
Similar observational studies over decades have been critical to our current knowledge base regarding alcohol. We also need randomized controlled trials to understand the potential benefits of different cannabinoid compounds.
If you are considering using alcohol or cannabis, here are a few things to keep in mind:
Alcohol is associated with adverse health effects
Some of my patients believe that drinking wine is beneficial and reduces the risk of heart attack. However, new research has challenged the notion that moderate drinking has cardiovascular benefits.
It’s clear that heavy drinking is associated with several cardiovascular risks, including high blood pressure, stroke and heart failure. Long-term heavy drinking is also linked to other serious health problems, such as depression and dementia. In addition, alcohol is a carcinogen, and moderate drinking is linked to an increased risk of several types of cancer. Even light drinking — half a drink a day — has been linked to a small increase in the incidence of breast cancer in women and colon cancer in men.
Alcohol can lead to traffic accidents and contributes to assault and suicide. In large doses, it can even cause respiratory depression and death.
Cannabis can also cause harm
Cannabis doesn’t cause respiratory depression, so it doesn’t cause what we call an “overdose.” However, potent cannabis use has been linked to acute psychosis, and in some cases this has resulted in death or suicide.
Contrary to popular belief, it is possible to become physically dependent on cannabis or to develop a cannabis use disorder. People who use cannabis frequently can become dependent and experience withdrawal symptoms if they cut down or stop using it. Individuals who use cannabis in a way that causes significant impairment may have a cannabis use disorder. These people may need treatment to reduce or stop use.
Most health claims about cannabis are not scientifically proven
Only three drugs containing cannabinoids have been approved by the FDA: dronabinol and nabilone contain synthetic THC and can be used to treat nausea and vomiting after chemotherapy in patients who have failed other drugs; CBD is used to treat rare forms of childhood epilepsy; and dronabinol is also approved to treat anorexia due to AIDS. Studies suggest that cannabis extracts may be useful in treating pain and spasticity associated with multiple sclerosis and that cannabinoids may be effective in treating neuropathic pain.
Although mainstream marketing practices — and countless anecdotal reports — tout cannabis as a proven treatment for anxiety, pain, insomnia, and more, all of these claims require more research before we can make firm recommendations. Cannabis use can actually complicate the treatment of depression.
But we shouldn’t confuse the potential therapeutic uses of pharmaceutical-grade cannabis with products sold in pharmacies. Many products in pharmacies can contain impurities, may not contain CBD, and have high THC concentrations.
Smoking and vaping cannabis comes with risks
A few years ago my patient had a heart attack. It was somewhat unexpected as he was healthy and physically active. Although I had documented that he was not a tobacco smoker, given his recent heart attack, I asked him again, “Do you smoke?”
He said no. Then he paused and clarified that he didn’t smoke tobacco. But he smoked cannabis every day after work and had for years. Although the available evidence is limited, some studies suggest that cannabis use, like tobacco use, is associated with heart attacks.
We need studies examining the health effects of smoking cannabis on a daily basis, as daily cannabis use is becoming more common among young adults and several studies show that those who use it daily are at higher risk of adverse health effects.
Our research group conducted several systematic literature reviews. We found that smoking cannabis was linked to coughing, wheezing and testicular cancer.
Concerns about THC use and mental health
Cannabis use during adolescence has been linked to the development of depression and suicide attempts in young adulthood. It’s also linked to psychosis, a potentially devastating disease in this age group.
Cannabis use among young adults hit an all-time high in 2021, according to the National Institutes of Health.
I am also concerned about older patients who take multiple medications and use cannabis as there is limited data on how the two interact. Cannabis use is increasing among older adults, but there is very limited data on its impact on this group.
Given the available evidence, I do not recommend alcohol or cannabis use to my patients for medical or psychiatric conditions.
Cannabis advocates like to say it’s “natural,” so it can’t be bad for us. We should remember that tobacco is also a “natural” green leafy plant. It has been used for thousands of years. But in the 20th century, the tobacco industry designed highly addictive products, sparking a worldwide epidemic of tobacco addiction and subsequent cancer, cardiovascular and lung diseases.
It’s clear what excessive drinking can do to our bodies and minds. It’s too early to tell what impact commercialized cannabis – and its ubiquitous use – will have on our health.
Salomé Keyhani is a professor of medicine at the University of California, San Francisco.
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