Extracted from the wood and bark of the *Acacia catechu* tree, catechu contains tannins that act as an astringent. People apply it to minor skin irritations and mouth sores to tighten tissues and calm inflammation.
Taken orally as a tea or tincture, it has a traditional history for easing diarrhea and soothing mild throat irritation. Doses depend on the form. Because its tannins can lower iron absorption, avoid catechu with iron-rich meals or supplements if you are anemic. Do not use it internally for long periods.