Tannic acid is found in the nutgalls formed by insects on twigs of certain oak trees (Quercus infectoria and other Quercus species). It is removed and used as medicine.
Historically, tannic acid was used along with activated charcoal and magnesium oxide in the “universal antidote,†formerly used for poisoning. These three ingredients in combination were believed to work better at absorbing poisons than any of the ingredients alone. Unfortunately, the activated charcoal soaked up the tannic acid, more or less inactivating it. This made the combination less effective.
These days, people apply tannic acid directly to the affected area to treat cold sores and fever blisters, diaper rash and prickly heat, poison ivy, ingrown toenails, sore throat, sore tonsils, spongy or receding gums, and skin rashes; and to stop bleeding.
Tannic acid is also taken by mouth and applied directly for bleeding, chronic diarrhea, dysentery, bloody urine, painful joints, persistent coughs, and cancer.
Vaginally, tannic acid is used as a douche for white or yellowish discharge (leukorrhea).
In foods and beverages, tannic acid is used as a flavoring agent.
In manufacturing, tannic acid is used in ointments and suppositories for the treatment of hemorrhoids; for tanning hides and manufacturing ink; and to kill dust mites on furniture.
