While overconsumption of some vitamins and minerals is proven to have negative effects in a quantifiable way, that’s not the case with biotin. “There is currently no established upper limit for biotin intake, due to a lack of reports of adverse events with high intake,” Cording explains.
More specifically, "no adverse effects have been observed at very high levels or oral intake, up to 200 milligrams daily (that's 20,000 micrograms), so there's no compelling data supporting a direct toxicity effect," adds Ferira.
A common misconception is that biotin supplements, or an increased intake of biotin in general, could lead to breakouts.
This, however, has not held up when studied. As board-certified dermatologist Hadley King, M.D. tells mbg, it has been theorized that biotin supplements could contribute to skin blemishes by interfering with the absorption of pantothenic acid (vitamin B5). “However, no studies have shown that taking biotin supplements or having a pantothenic acid deficiency cause [breakouts],” King says.
Additionally, as Ferira notes: "It's not quite that simple, because caution should be placed on high-dose biotin due to potential for lab testing interference for key biomarkers."
A case of too much of a good thing, "biotin megadosing can prove challenging for the accurate assessment of key labs, including vitamin D levels as measured by serum 25-hydroxyvitamin D, troponin for cardiac function, HCG for pregnancy testing, thyroid panel results, and others." For this reason, "more is not more in the base of biotin, at least not at these extreme, high levels like 5 milligrams (5,000 micrograms) and up," Ferira concludes.
Again, please consult with your health care practitioner for your own unique needs. As Ferira expounds, "there are certainly specific clinical scenarios under the care of a doctor where intentional, high-dose biotin regimens are utilized, but that's not what we're talking about here for the average individual."