Much has been made in the lay-press about the safety of cannabis or cannabidiol (CBD).  Compared to some medications, cannabis and CBD are, in fact, very safe.  However, as we gain more rigorous understanding of these medications, it is clear that they are not entirely benign.  Today we will focus on the risk posed by cannabis or CBD interacting with medications that you may be taking.  

The risk from these interactions stems from either THC or CBD causing the level of the conventional medication to go either up or down.  Generally, conventional medications are safe and effective within a range of blood level.  If the level gets too high, it can be toxic.  If the level gets too low, the medicine can cease to work, which can be very dangerous too. 

Below you’ll find two tables.  The first table contains the conventional medications that Dr. Google tells me that you’re asking about.  The second table contains the medications that I see in my practice that you should know about if you’re taking.  

There is a column for CBD and a column for THC (cannabis).  You’ll note that there are three designations in the columns (Y = there is an interaction, beware!  N = no or no significant interaction.   T = theoretical interaction but not seen or not concerning in the real world.)

As you can see, most of the meds that you asked about are relatively unaffected by either CBD or THC.  The group of medications that I added are more concerning and are affected mostly by CBD.  

Medications that are trending on Google:

Adalimumab (Humira) N N
Advair (fluticasone/salmeterol) N N
Albuterol (Ventolin) N N
Amlodipine (Norvasc) N N
Amoxicillin N N
Aripiprazole (Abilify) N T
Azithromycin (Zithromax, Z-PAK) N N
Esomeprazole (Nexium) Y N
Etanercept (Enbrel) N N
Hydrochlorothiazide N N
Infliximab (Remicade) N N
Lantus Solostar (insulin glargine) N T
Ledipasvir and sofosbuvir (Harvoni) N N
Levothyroxine (Synthroid) N N
Lisdexamfetamine (Vyvanse) N N
Lisinopril (Prinivil, Zestril) N N
Metformin (Glucophage) N N
Pregabalin (Lyrica) N N
Riotropium (Spiriva Handihaler) N N
Rosuvastatin (Crestor) N N
Simvastatin (Zocor) N T
Sitagliptin (Januvia) N T
Sofosbuvir (Sovaldi) N N

Medications that concern us:

Amiodarone (Pacerone) Y N
Cetirizine (Zyrtec) N N
Clonazepam (Klonopin) N N
Clopidogrel (Plavix) N T
Eszopiclone (Lunesta) N N
Everolimus (Afinitor) Y T
Loratadine (Claritin) Y T
Lorazepam (Ativan) Y T
Quetiapine (Seroquel) N T
Remeron (Mirtazapine) Y N
Tacrolimus (Protopic, Prograf) Y Y
Trazadone (Desyrel) N N
Warfarin (Coumadin) Y T
Zolpidem (Ambien) N N

Of course, these are not complete lists and you should be aware that many medication-checker websites and applications are not complete or accurate when it comes to cannabis or CBD.  The above lists cannot be considered medical advice and you should consult a qualified Cannabinoid Specialist before using cannabis or CBD, especially in conjunction with conventional medications. 

So what do we tell our patients about these interactions?

Let’s address CBD first.  CBD has the most significant interactions due to the way the body breaks down CBD and various conventional medications.  Since there are no proven benefits to CBD in humans (except in children with rare genetic seizure disorders), I do not recommend CBD.  As more data become available on CBD, this may change, and it may become more important to keep an eye on those interactions.

Over the counter medications are also prone to interact.  Let me call your attention to the interaction between CBD and Loratadine (Claritin).  Claritin is generally well tolerated and is especially useful now in pollen season.  However, CBD can raise Claritin level and at toxic levels Claritin can cause dangerous heart rhythms that can be lethal.

As you can also see in the charts, the interactions caused by THC are mostly theoretical.  In many cases, those interactions are that the combo may make you more sleepy than either drug alone.  Usually this is not really a problem.  There are some very concerning interactions, like Tacrolimus.  Thankfully, we can monitor this, and not many folk take this medication.

A key point that I hope you can see, is that these medication interactions are common with common medications and that the risk from neither cannabis nor CBD can be taken lightly.  In particular, it is unwise to rely on the budtender to know this information and give you adequate advice.  In fact, the budtenders don’t know the information that doctors know, nor do they know enough about your illness and care to be able to give advice.  Unfortunately, this doesn’t stop them.

Consult with a Qualified Boston Medical Marijuana Expert Today 

Those considering using THC, CBD, or any type of medicine found in cannabis to help manage their condition should consider speaking to a trained medical expert who is knowledgeable about using cannabis therapeutically. Massachusetts medical marijuana doctor Jordan Tishler, M.D. sits on the faculty of Harvard Medical School and has years of experience helping patients treat pain and other ailments using cannabis. He and the team at InhaleMD stand ready to assist patients in determining whether medical marijuana is right for them. For more information, or to set up a virtual consultation with the team at InhaleMD, call us at (617) 477-8886 today.

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