I've also read that tea tree shouldn't be swallowed. Remember there are two types of tree oil, one is an ointment designed to treat chapped lips. The other is an extract that I again use to both disinfect the toothbrush, and mouth cavity without swallowing. I believe that if an fungus is present in the mouth, than using the same toothbrush with hours to marinate in the residue from the mouth didn't make sense to me. But if you can find another method that takes care of both I am willing to give it an try.