marijuana drug interactiions

Essential Marijuana Drug Interactions You Need to Know

Essential Marijuana Drug Interactions You Need to Know

As of December 2020, more than 5.4 million Americans across 35 states have a medical marijuana card. As you can guess, many of these people would be using other prescription or non-prescription drugs. Also, the federal government estimates more than 90 million Americans use marijuana once or twice a week. Whenever an individual is using more than one medicine, the possibility of drug-drug interactions is always a worry. Marijuana drug interactions are a danger for medical professionals and patients alike.

Statistics from the CDC show that about 1.3 million Americans are hospitalized every year due to medication errors (including drug interactions). Due to the current federal status of marijuana, there haven’t been extensive investigations into its potential interaction with other drugs. Given this, most available studies do not provide conclusive evidence and marijuana drug interactions. This fact could be a problem for medical marijuana users using other medications. In this article, we’ll highlight some of the most common and probably most important interactions of marijuana with other drugs.

Of note, there has been no record of death following marijuana or dronabinol Marinol use. Nor are there any recorded deaths even when combined with other drugs. However, medical marijuana users have to be conscious of these interactions. This insight ensures the effectiveness of their medications and prevents unforeseen side effects.

As a rule, you should always inform all of your doctors or pharmacist about marijuana use. This especially when you are about to add a new drug to your regimen. They are in the best position to educate you about possible interactions and side effects.

Some Conventional Medicines that Interact with Marijuana


Marijuana has the potential to interact with Viagra, by far the most popular drug for erectile dysfunction. The potential interaction occurs at the metabolic level. Marijuana precipitates the interaction to inhibit Cytochrome P450 enzyme. Viagra, as well as other drugs that are metabolized by this set of enzymes, remain in the bloodstream for longer. Therefore, combining it with either cannabis Sativa or cannabis Indica leads to higher concentrations. According to Mayo Clinic, the interaction of marijuana with Viagra “may cause increased effects or potentially serious adverse reactions.”

The National Institute for Drug Abuse recognizes that marijuana raises ones’ heart rate for up to 3 hours after smoking. This effect may increase the chance of heart attack. Older users and those with heart problems may be at higher risk.

Researchers have reported a possible case of marijuana and viagra interaction. The affected individual, a 41-year-old man as rushed into the emergency ward following a heart attack. The researchers suspected that the heart attack might have been as a result of the concomitant use of marijuana and cannabis. There are many other cases of people having a heart attack following the recreational use of Viagra. This before the addition of cannabis.


Warfarin is another drug that is metabolized by the cytochrome P-450 enzymes. It’s commonly prescribed to prevent or resolve the clotting of blood in the veins and arteries. This type of clotting occurrence may lead to heart attack, stroke, or other dangerous conditions.

The cannabinoids in marijuana can inhibit the enzymes responsible for metabolizing warfarin. Consequently, cannabis can exacerbate the effects of warfarin in the body, ultimately leading to severe bleeding. Medical staff reported one such case in 2009. The Cheyenne Veterans Affairs Medical Center in Wyoming admitted a 56-year older adult into their facility. The patient presented with stomach bleeding, and he confessed to smoking marijuana frequently while also being on warfarin.

The said patient spent a week in the hospital, after which time the staff discharged him. Fifteen days later, the patient came back with similar complaints of bleeding - this time, through the nose. The case report states the medical staff counseled the patient on the potential drug interactions between marijuana and warfarin. The medical team advised the patient about the need to stop smoking while on warfarin. The patient stopped smoking marijuana and did not present with bleeding complaints during the follow-up period.


Doctors commonly prescribe benzodiazepines for their anxiolytic, muscular relaxant, and sedative properties. Many people even self-medicate on drugs like Xanax or Valium whenever they are having trouble sleeping. Some studies suggest mixing benzodiazepines with cannabis could lead to excessive central nervous system depression. Nabilone is a synthetic cannabinoid approved for the treatment of nausea and vomiting associated with chemotherapy. Nabilone package inserts include this warning.

Marijuana potentiates the effects of benzodiazepines. Users may feel drowsier than usual, and the drug may decrease the breathing and heart rates. In extreme conditions, this could lead to loss of consciousness. The increased drowsiness makes it even more challenging to operate moving machinery or drive. Sleepiness is a standard warning associated with sedatives and other CNS depressants.

Antidiabetic Medication

Research on the relationship between marijuana and antidiabetic medications has thus far been inconclusive. Despite this, there appears to be enough evidence to show that marijuana could affect blood sugar levels. Some studies show that frequent marijuana use could make an individual less resistant to the effects of insulin. Consequently, such people would be able to achieve tighter control over their blood sugar levels.

Other studies have reported that marijuana use puts an individual at a higher risk of developing slightly elevated blood sugar levels. However, the confusing reports from different studies make it difficult to arrive at a definite conclusion. In essence, we do not know what the potential impact of marijuana is on antidiabetic medications. We do realize, however, that there is a real possibility of interaction. Thus, we need to closely monitor marijuana users that are also on antidiabetic medicines strictly.

Fluoxetine and Ketoconazole

The antidepressant and antifungal medications are capable of inhibiting Cytochrome P450 enzymes. When used concomitantly with marijuana, they may slow down the rate at which it clears THC from the body. Higher tetrahydrocannabinol THC concentrations lead to a more intense high. At higher levels, users would be more likely to experience the side effects of THC.

In a 1991 case*, a 21-year old patient on fluoxetine presented with severe mania and psychosis. Investigations revealed that the patient smoked marijuana after using fluoxetine. The hypothesis was that the symptoms were likely a result of the high THC concentration.


The antituberculosis medication is a known inducer of the cytochrome P450 enzymes, the enzyme set responsible for the metabolism of marijuana. When rifampicin combines with medical marijuana, it has the potential to accelerate the metabolism of THC. Hence, rifampin clears THC from the bloodstream at a faster rate than usual. By implication, you may experience a lesser high than you are used to when you take marijuana alongside rifampicin.

Marijuana and Alcohol Interaction

Although alcohol isn’t precisely a drug, it still makes our list and demands special attention. This fact because mixing marijuana and alcohol is especially frequent among recreational drug users. People commonly combine cannabis and alcohol. As marijuana for recreational purposes becomes legal in many states, this practice is sure to increase. Studies have shown that people who use alcohol and marijuana together

Mechanisms of Action

The way these two substances work in the brain is different. Marijuana affects cannabinoid receptors. Alcohol primarily affects inhibitory and excitatory neurotransmitters. Despite having different mechanisms of action, they are synergistic and share similar effects. Research suggests combining them enhances the impact of each.

Clinical research shows that people using alcohol and marijuana together have more THC in their system. Alcohol also lasts in the bloodstream for longer.

Asides the interaction at the metabolic level, alcohol is also known to widen the blood vessels in the gastrointestinal tract. This interaction is thought to allow for faster absorption of the THC. The overall effect is usually a more intense high that could knock off even the most experienced marijuana users.

Side Effects

Shared effects include sedation, alterations in judgment and perception, and distortion of time. Both have some minor hallucinogenic effects. Physical effects include slowed reflexes and decreased coordination. Both marijuana and alcohol decrease judgment leading to poor decision making and diminished rational thinking. Marijuana can increase the dehydration associated with the loss of urine seen with alcohol. Alcohol increases the side effects of marijuana, including hallucinations, paranoia, and anxiety.

Chronic Abuse

Chronically abusing both drugs together, worsens the physical dependence on either drug alone. Routinely using both drugs is also strongly associated with having some other form of mental illness. These conditions include depression, an eating disorder, or an anxiety disorder.

Marijuana and alcohol interaction could be particularly dangerous because of the risk of overdosing on alcohol. Combining cannabidiol CBD products with alcohol increases the potential for alcohol poisoning.

When using cannabis for any medical purpose, it is essential to get legal. Self-medicating for chronic pain or other medical conditions could put you at risk. At Kind Health Florida, our certified marijuana doctors will evaluate your case and help you obtain your medical marijuana card. Call us today to schedule an appointment.

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*Stoll, A. L., Cole, J. O., & Lukas, S. E. (1991). A case of mania as a result of fluoxetine-marijuana interaction. The Journal of Clinical Psychiatry, 52(6), 280-281

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