Dear tom_is_here Thanks for contacting us. The interference studies that we have carried out do not show any connection between increased levels of biotin and false negative test results. Free biotin clears quickly from the system and a 350 microgram dose should clear in 24 hours, so, if you are still concerned, and if your prescriber of the biotin supplement agrees, you could delay the intake of your supplement so that there was at least 24 hours between your last dose and taking the test. You could then take the biotin supplement after testing. That way you could be certain that there would be no interference. I hope that this helps and answers your question. Kind regards Gary Carpenter