The oak tree, respected for millennia as a source of strong,
dense wood, also has a considerable tradition of medicinal use.
The astringent, tannin-rich bark of the oak tree has been
recommended for such diverse conditions as internal hemorrhage,
diarrhea, dysentery, cancer, and pneumonia. What is Oak Bark
Used for Today? Germany’s Commission E recommends oak bark
internally for treatment of and topically for eczema. However,
there is no meaningful scientific evidence that oak bark offers
any therapeutic benefit in these or any other conditions. Only
double-blind, placebo-controlled studies can prove a treatment
effective, and none have been performed on oak bark. (For more
information on why such studies are essential, see Why Does This
Database Rely on Double-blind Studies?) Oak bark contains
numerous substances in the tannin family, especially
ellagitannin,1 along with potentially active substances in the
saponin family.2 Tannins are thought to have an astringent
effect, meaning that they reduce tissue swe