Astringent

Tannins, being a kind of polyphenol, bind salivary proteins and make them precipitate and aggregate,[3][4][5] producing a rough, "sandpapery", or dry sensation in the mouth.

[10] Mild astringents relieve such minor skin irritations as those resulting from superficial cuts; allergies; insect bites;[9] anal hemorrhoids;[11] and fungal infections such as athlete's foot.

[citation needed] Some common astringents are alum, acacia, sage,[13] yarrow,[14] witch hazel, bayberry, distilled vinegar, very cold water, and rubbing alcohol.

[16] Calamine lotion, witch hazel, and yerba mansa, are astringents,[17] as are the powdered leaves of the myrtle.

The tannins in some teas, coffee, and red grape wines like Cabernet Sauvignon and Merlot produce mild astringency.

A crystal of the astringent alum
The astringents and acids in fresh blackthorn berries (sloes) give the fruit its sourness.