Thyroid function test (TFT) is one of the most commonly performed hormonal evaluations. Abnormalities can be detected in TFT reports in euthyroid individuals due to various reasons. One such important, but overlooked cause is the interference from concomitant medication usage. Several drugs, ranging from over-the-counter (OTC) vitamin supplements to specialised anti-cancer medicines can affect the estimation of any of the components of TFT [thyroid-stimulating hormone (TSH), total thyroxine (TT4), total tri-iodothyronine (TT3), free thyroxine (FT4) or free tri-iodothyronine (FT3)].