Educational information, not medical advice — ask your doctor or midwife.
Mazu is the dried gall (a hard, round growth) that forms on the twigs of the oak tree Quercus infectoria after a small wasp lays its eggs there. It is a single drug in the Persian and Unani traditions, not a mixture. It is used mainly as an astringent, meaning it makes tissue draw together and tighten.
Traditional practitioners use it as a mouthwash or gargle for sore gums and throat, as a wash or ointment for weeping skin and piles (haemorrhoids), and in small internal doses for loose stools. It is very rich in tannins, the same bitter, puckering compounds found in strong black tea.
The honest verdict: Mazu has deep and wide traditional standing, but good human trials are essentially missing. Long traditional use is not proof that something works, and that gap applies to every use listed on this page.
Mazu is thought to work almost entirely through its tannins. Tannins bind to proteins on the surface of skin, gums and gut lining, forming a thin protective layer that feels tight and dry.
That same binding action may reduce oozing, slow minor bleeding from surface tissue and firm up loose stools. Laboratory work also shows the extract slows the growth of several bacteria and fungi in a dish.
These are plausible explanations, not proven ones. What happens in a test tube often does not happen in a person, and this has not been properly tested in people.
Mazu is sold whole, as a coarse powder, or as a dark extract. Whole galls are usually crushed or ground just before use.
Common preparations include a decoction (simmered water extract) used as a gargle or wash, a powder dusted onto weeping skin, and ointments or suppositories for piles. Powder is also blended into tooth powders and mouthwashes.
Internal use, when it happens at all, is small amounts of powder in water or honey. Concentrated tannic acid extracts sold for internal use are a different and riskier product.
Mazu appears in Persian and Unani medicine from the classical period onward, and is described in the works of Avicenna (Ibn Sina) and later Unani compendia as a strong drying and binding drug. It also has a long record in Ayurveda as majuphal and in Chinese medicine as mo shi zi.
It was widely traded, and for centuries the same galls were the main source of iron gall ink and of tanning material for leather. Its medicinal reputation in every tradition rests on the same property: it tightens and dries tissue.
See a doctor if diarrhoea lasts more than two days, if there is blood in your stool, or if you have a fever with it. Get urgent care for yellowing of the skin or eyes, dark urine, severe stomach pain or ongoing vomiting, as these can be signs of liver trouble. Also see a dentist or doctor for a mouth ulcer lasting more than three weeks, for bleeding from the back passage, or for any skin patch that spreads, smells bad or leaks pus.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Mazu is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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