***Please note that blog is not to be considered medical advice. Always consult your physician for more information and/or questions related to your specific medical history***
Types of Interactions
THC and CBD are both metabolized through the liver by the same liver enzymes that metabolize around 60% of the prescription medications many individuals take. Therefore, when taking a dose of THC or CBD with prescription meds, there could be an interaction (with CBD generally more likely to interact than THC).
Generally speaking, there are a few different reactions that could occur with cannabis and prescription medications. The first being where the prescription medication’s levels change and either become very low or very high, both of which can be dangerous. Second, there are the drugs that cause sedation, just like THC does, so taking THC with some of these drugs may increase the effects of sedation. Additionally, other reactions can also occur with certain drugs that don’t activate in the system until they are metabolized in the body where they become active. An example of this is the drug Gabapentin Enacarbil, a form of Gabapentin that our body metabolizes differently than a regular or extended-release form of Gabapentin. Furthermore, although the research is limited, CBD and THC have also been shown to affect Warfarin, Theophylline, and Clobazam, which are very common medications.
One thing to touch on is that opioids and cannabinoids haven’t generally been shown to have a negative interaction. Research shows that people who consume opioids and cannabis together may actually decrease their opioid doses.
AGAIN, IT IS WORTH REPEATING THAT YOUR SHOULD ALWAYS TALK YOUR DOCTOR REGARDING YOUR PRESCRIPTION MEDICATIONS AND HOW THEY MAY INTERACT WITH CBD OR THC.
The Grapefruit Effect
While it may seem unrelated, grapefruit is similar to THC and CBD in the fact that it is metabolized by the same liver enzymes as many prescription medications. Many physicians will also warn a patient not to take a particular medication with grapefruit because it too can affect how the medication is metabolized in their body and cause an interaction.
The following list provides some common drug categories and specific medications that have a “grapefruit” warning. While not yet fully proven, they could cause some issues if consumed with THC and/or CBD.
Antibiotics and Antimicrobials
Amoxicillin, Penicillin Gentamicin, Tetracycline, Tobramycin, Cefalexin, Doxycycline, Ciprofloxin, Azithromycin, Sulfamethoxazole, Augmentin, Flagyl, Amoxil, Cipro, Keflex, Bactrim, Levaquin, Zithromax, Avelox, Cleocin
Anticancer Medications
Abraxane, Adriamycin, Carboplatin, Cytoxin, Daunorubicin, Doxil, Ellence, Fluoricil, Gemza, Halavan, Ixempra, Methotrexate, Mitomycin, Mitoxantrone, Tamoxifen, Taxol, Taxotere, Thiotepa, Vincristine, Xeloda
Antihistamines
Zyrtec, Chlor-Trimeton, Benadryl, Allegra, Claritin, Alavert
Antiepileptic Drugs
Keppra, Carbamazapine, Gabapentin, Depakote, Lamotagrine, Dilantin, Topiramate Clobazam, Tegretol, Lyrica, Lamictal, Phenytoin
Blood Pressure/Blood Thinner Medications
Lisinopril, Norvasc, Losarten, Hydrchlorothiazide, Metoprolol, Carvedilol, Furosemide, Cozaar, Clonidine, Toprol-XL, Lasix, Valsartan, Prinivil, Zestril, Coreg, Ramapril, Vasotec, Labetalol, Diovan, Lopressor, Toprol XL, Lasix, Microzide, Clopidogrel/Plavix, Warfarin/Coumadin
Cholesterol Medications
Lipitor/Atorvastatin, Lovastatin/Mevacor, Pravastatin/Pravachol, Rosuvastatin/Crestor, Simvastatin/Zocor, Ezitimibe/Zetia, Fenofibrate/Tricor, Gemfibrozil/Lopid
Corticosteroids
Cortisone, Prednisone, Methylprednisolone, Dexamethasone, Betamethasone, Hydrocortisone
Erectile Dysfunction Medications
Avanafil/Stendra, Sildenafil/Viagra, Tadalafil/Cialis, Vardenafil/Levitra
GI Medications for GERD or Nausea
Nexium/esomeprazole, Protonix/Pantoprazole, Prevacid, Aciphex, Prilosec/Omeprazole, Zofran/Ondansetron, Promethazine, Reglan, Meclizine, Transdermal Scopolamine Patch
Heart Rhythm Medications
Amiodarone/Cardarone, Flecainide/Tambocor, Procainamide/Procan, Quinidine, Tocainide, Inderal/Propranolol
Immunosuppressants
Prednisone, Cyclosporin, Neoral, Prograf, Inuran, Azathioprine, Tacrolimus
Medications to Treat Anxiety, Depression, and Other Mood Disorders
Citalopram/Celexa, Escitalopram/Lexapro, Fluoxetine/Prozac, Paroxetine/Paxil, Sertraline/Zoloft, Olanzapine/Zyprexa, Quetiapine/Seroquel, Risperidone/Risperdal, Geodon, Clozapine, Lithium, Valproic Acid, Ativan/Lorazepam, Trazadone, Ambien/Zolpidem, Clonazepam/Klonopin, Valium/Diazepam
Pain Medications (may increase side effects of these meds, but may also work together)
Codeine, Fentanyl, Hydrocodone, Hydromorphone/Dilaudid, Meperidine, Oxycontin, Oxycodone, Tramadol, Norco, Vicodin, Lortab, Demerol, Percocet, Roxicet
Prostate Medications
Terazosin/Hytrin, Tamsulosin/Flomax, Silodosin/Rapaflo, Prazosin/Minipress, Doxazosin/Cardura, Alfuzosin/Uroxatol
Finally, below are several other medications that should be closely monitored when co-administered with cannabinoids because they are metabolized by similar liver enzymes and may affect how the prescription medication will work in the body.
Acenocoumarol, Alfentanil, Aminophylline, Amiodarone, Amitriptyline, Amphotericin B, Argatroban, Busulfan, Carbamazepine, Clindamycin, Clomipramine, Clonidine, Clorindione, Cyclobenzaprine, Cyclosporin,Dabigatran Etexilate, Desipramine, Dicoumarol, Digitoxin, Dihydroergotamine, Diphenadione, Dofetilide, Dosulepin, Doxepin, Ergotamine, Esketamine, Ethinyl Estradiol, Ethosuximide, Ethyl Biscoumacetate, Everolimus, Fentanyl, Fosphenytoin, Imapramine, Levothyroxine, Lofepramine, Melitracen, Meperidine, Mephenytoin, Mycrophenolic Acid, Nortriptiline, Paclitaxel, Phenobarbitol, Phenytoin, Pimozide, Propofol, Quinidine, Sirolimus, Tacrolimus, Temsirolimus, Theophylline, Thiopental, Tianeptine, Trimipramine, Valproic Acid, Warfarin, Phenprocoumon
References
Antoniou T, Bodkin J, Ho JM. Drug interactions with cannabinoids. CMAJ. 2020;192(9):E206. doi:10.1503/cmaj.191097
Yamaori S, Koeda K, Kushihara M, Hada Y, Yamamoto I, Watanabe K. Comparison in the in vitro inhibitory effects of major phytocannabinoids and polycyclic aromatic hydrocarbons contained in marijuana smoke on cytochrome P450 2C9 activity. Drug Metab Pharmacokinet. 2012;27(3):294-300. doi: 10.2133/dmpk.dmpk-11-rg-107. Epub 2011 Dec 13. PMID: 22166891.
Rebecca L Hartman, Timothy L Brown, Gary Milavetz, Andrew Spurgin, David A Gorelick, Gary Gaffney, Marilyn A Huestis, Controlled Cannabis Vaporizer Administration: Blood and Plasma Cannabinoids with and without Alcohol, Clinical Chemistry, Volume 61, Issue 6, 1 June 2015, Pages 850–869, https://doi.org/10.1373/clinchem.2015.238287
Stout SM, Cimino NM. Exogenous cannabinoids as substrates, inhibitors, and inducers of human drug metabolizing enzymes: a systematic review. Drug Metab Rev. 2014 Feb;46(1):86-95. doi: 10.3109/03602532.2013.849268. Epub 2013 Oct 25. PMID: 24160757.
Geffrey AL, Pollack SF, Bruno PL, Thiele EA. Drug-drug interaction between clobazam and cannabidiol in children with refractory epilepsy. Epilepsia. 2015 Aug;56(8):1246-51. doi: 10.1111/epi.13060. Epub 2015 Jun 26. PMID: 26114620.
Alsherbiny MA, Li CG. Medicinal Cannabis-Potential Drug Interactions. Medicines (Basel). 2018;6(1):3. Published 2018 Dec 23. doi:10.3390/medicines6010003
Kocis, P. T., & Vrana, K. (2020). Delta-9-Tetrahydrocannabinol and Cannabidiol Drug-Drug Interactions. Medical Cannabis and Cannabinoids, 3(1), 61-73. https://www.karger.com/Article/Abstract/507998
CBD Oil Review, Blood Pressure Medication and CBD Oil Interactions, Jason Brett, February 9, 2021
Medical News Today, Everything You Need to Know About Anxiety Medications, Jayne Leonard, January 13, 2020
Cichewicz DL. Synergistic interactions between cannabinoid and opioid analgesics. Life Sci. 2004 Jan 30;74(11):1317-24. doi: 10.1016/j.lfs.2003.09.038. PMID: 14706563.
Abrams DI, Couey P, Shade SB, Kelly ME, Benowitz NL. Cannabinoid-opioid interaction in chronic pain. Clin Pharmacol Ther. 2011 Dec;90(6):844-51. doi: 10.1038/clpt.2011.188. Epub 2011 Nov 2. PMID: 22048225.
Parihar V, Rogers A, Blain AM, Zacharias SRK, Patterson LL, Siyam MA. Reduction in Tamoxifen Metabolites Endoxifen and N-desmethyltamoxifen With Chronic Administration of Low Dose Cannabidiol: A CYP3A4 and CYP2D6 Drug Interaction. J Pharm Pract. 2020 Nov 15:897190020972208. doi: 10.1177/0897190020972208. Epub ahead of print. PMID: 33191836.
