Does cannabis affect thyroid? I am hypothyroid and take natural desiccated thyroid.


There is little in the way of evidence that discusses hypothyroidism, TSH levels and medicinal cannabis use. TSH levels can be affected by a multitude of things including medications. It is important to consider drug to drug interactions when using cannabis.

The Department of Health (DC) notes the following drug interactions with cannabis.

THC can decrease serum concentrations of clozapine, duloxetine, naproxen, cyclobenzaprine, olanzapine, haloperidol, and chlorpromazine (Flockhart 2007, Watanabe et al 2007).

CBD is a potent inhibitor of CYP3A4 and CYP2D6. As CYP3A4 metabolizes about a quarter of all drugs, CBD may increase serum concentrations of macrolides, calcium channel blockers, benzodiazepines, cyclosporine, sildenafil (and other PDE5 inhibitors), antihistamines, haloperidol, antiretrovirals, and some statins (atorvastatin and simvastatin, but not pravastatin or rosuvastatin). CYP2D6 metabolizes many antidepressants, so CBD may increase serum concentrations of SSRIs, tricyclic antidepressants, antipsychotics, beta blockers and opioids (including codeine and oxycodone).

THC and CBD increase warfarin levels. Smoked cannabis can decrease theophylline levels.

Wendy NP

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