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Can I Take Cannabis With Other Medications?

top view of various pills inside a plastic cup beside a cannabis leaf in purple background

One of the first questions medical marijuana cardholders ask is, “Can I take cannabis with other medications?

Drug interactions with cannabis are important information for patients who value their health. Often, medical marijuana cardholders are dealing with chronic conditions. Many cannabis cardholders have been under doctor treatment and are taking prescribed medications as directed. These patients are prudent to ask about medical cannabis and possible drug interactions.

These prudent medical marijuana cardholders have one pressing concern: Is it safe to mix medical marijuana with other prescribed medications?

As a disclaimer, medical marijuana cardholders should be well aware that the American Medical Association’s (AMA’s) research into how medical marijuana interacts with other drugs is relatively recent and less than complete.

CYP3A4*2 - The CYP enzyme, which metabolizes drugs in the liver.
CYP3A4*2 – The CYP enzymes are found in the liver, and are responsible for the metabolization and processing of various types of drugs. It is a subtype of the CYP450 group of enzymes. From Wikimedia Commons. By Mohmmed Laique. CC BY-SA 4.0.

Before embarking upon a course of medical marijuana treatment, medical marijuana cardholders should whenever possible contact their doctor and discuss any potential interactions of prescribed medications and medical marijuana.

Drug interactions with cannabis may vary. The medical marijuana cardholder is responsible for researching as much as can be known about cannabis and possible drug interactions. When dealing with medical cannabis drug interactions, be sure to make the most-informed decision possible.

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Marijuana/Cannabinoid Drug Interactions – The Grapefruit Effect

The liver is key to drug interactions with cannabis. The liver uses enzymes, particularly one called CYP3A4, to metabolize and eliminate medical marijuana and other drugs from the body.  Aside from filtering out medical marijuana and other medications, the CYP enzymes are the primary culprits in causing drug interactions with cannabis. Cannabidiol (CBD) blocks CYP3A4, in a similar way that grapefruit does.

The CYP enzymes don’t act the same with every prescription drug and medical marijuana. Some drugs interfere with the job being done by CYP3A4. This interference can block the metabolic processing of cannabis and other drugs. The interference in turn creates a backlog of drug concentrations waiting to be expelled from the body. Anytime the liver is holding an extra bag of drug concentrations, conditions are ripe for toxic side effects from prescription drug interactions with cannabis.

Here are some medical cannabis and possible drug interactions to avoid, or consider carefully and monitor closely, advisably with a physician’s input. Although these interactions can be negative, it is worth remembering that, in some instances, cannabis may help replace the need for more addictive or damaging prescription drugs.

Grapefruit juice; drug interaction; enzyme; liver enzyme; contraindication; how grapefruit affects drug metabolism; drug metabolism.
FDA graphic by Michael J. Ermarth.

Warfarin: Common brands: Jantoven, Coumadin

Prescribed to treat and prevent blood clots, Warfarin can become too effective when the drug interacts with tetrahydrocannabinol (THC) and CBD. THC and CBD interactions with the CYP2C9 enzyme can raise Warfarin levels, causing excessive bleeding.

Theophylline: Common brands: Theo-24, Theochron, Elixophylline

People who have asthma, emphysema or chronic bronchitis and are being treated with Theophylline for these lung conditions should beware of possible drug interactions with medical cannabis. Smoking medical marijuana speeds up the liver’s clearing out of Theophylline, weakening the drug’s effectiveness. The drug’s interactions with cannabis may be less risky with edibles.

Clobazam: Common brands: Onfi

Is it safe to take CBD with other medicines? Consider Clobazam, a sedative used to minimize seizures such as caused by Lennox-Gastaut Syndrome (LGS), a severe form of childhood epilepsy. CBD interacts with the drug Clobazam by increasing its effects. Some physicians take advantage of the CBD drug interaction by prescribing CBD in conjunction with Clobazam. Taking into account the CBD interaction with the drug Clobazam, doses are adjusted to minimize its  sedative side effects..

Valproate: Brand names: Epilim, Episenta, Epiva

A multipurpose anticonvulsant, Valproate is prescribed to treat seizures, level out the manic episodes of bipolar disorder and even mitigate migraine headaches.

The CBD drug interaction with Valproate again gives a negative answer to the question, is it safe to take CBD with other medications? Clinical studies have found that mixing prescription CBD (Epidiolex) with Valproate can elevate liver enzyme counts to a level that will cause permanent liver injury. Definitely consult a doctor about potential medical marijuana/cannabis drug interactions if taking Valproate.

Medical Cannabis and Psychiatric Medications

Anxiety and depression are two common conditions medical marijuana cardholders hope to treat. Although research is incomplete, medical professionals urge that caution should be taken concerning medical cannabis interactions with psych meds.

The United Kingdom’s National Health Service (NHS) points out that cannabis is known to interact with psychiatric medications. Cannabis drug interactions are particularly noted with tricyclic antidepressants (TCAs), such as Amitriptyline, Imipramine and Dothiepin.

If a medical marijuana cardholder uses medical cannabis while being treated with tricyclic antidepressants and notices a speedy heartbeat (tachycardia) or a spike in blood pressure (called hypertension when the spike endures), chances are a psychiatric drug interaction with cannabis has occurred. To be cautious, pause the medical cannabis use and consult a primary caregiver.

There is a danger that cannabis interacting with tricyclic antidepressants will result in the medical marijuana cardholder becoming confused and restless and subject to hallucinations and mood swings. View such severe medical marijuana interactions with prescription drugs as red flags.

According to the NHS, insufficient research has been done on medical cannabis and possible drug reactions with antidepressants of the SSRI (Selective Serotonin Reuptake Inhibitor) family. The same source states that CBD and THC interactions with the drug Lithium, used to treat bipolar disorder, appear to be benign. Still, the question is CBD or THC safe to take with Lithium is yet to be conclusively answered.

If experiencing a medical cannabis interaction with tricyclic antidepressants and similar drugs, do not discontinue psychiatric medications except under the care of a physician.

One great thing about medical cannabis and interactions with other drugs, is the medical marijuana cardholder can always pause on the cannabis regimen and start it up later.

Medical Cannabis and Opioids

CB1 receptors, which are the receptors THC attaches to and cause a psychoactive effect, are found in the same areas of the brain as opioid receptors. In fact, cannabinoid receptors can “talk” to opioid receptors and influence the way they signal pain. This is one reason why cannabis can reduce painkiller intake, but also the reason why painkiller intake must be tapered in order to reduce the chances of a synergistic effect and opioid overdose.

Medical Cannabis and Antibiotics and Immunosuppressants

Cannabinoids have potent anti-inflammatory properties, and CBD in particular has immunosuppressive properties as well. This means that cannabis can dampen the immune system. This can be very useful for autoimmune disorders, cytokine storms, arthritis, chronic pain and other problems where out-of-control inflammation is common, which is many of them! It must be noted that cannabinoids like cannabigerol (CBG) have antibiotic properties.

There is no definitive evidence that cannabis interferes with antibiotics, and in fact may make them more effective in some instances. As CBD is a natural immunosuppressant, those using other immunosuppressant drugs (e.g. steroids such as Prednisone, anti-rejection tablets for organ transplants) ought to ask their physician about any potential negative or positive interactions. CBD could be very useful for kidney transplant patients, but more research is required in this area.

Cannabis and Prescription Drug Interaction: Conclusion

The fact is, we know very little about the precise ins-and-outs of how various cannabinoids interact with different drugs. There is a list available here, where you will notice that the most common classes of drugs cannabis can have a moderate or severe interaction with are:

  • Opioids and opiates
  • Benzodiazepines, barbiturates and other sedatives
  • Antidepressants and antipsychotic medications
  • Some types of steroids

However, as we know, it is important to take into account the various effects of different cannabinoids on the endocannabinoid system and other receptors. Different cannabinoids will have different effects, so it’s important to realize that not all cannabis is the same.

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