Oak Galls (Quercus infectoria, Manjakani) in Women's Intimate Health: A Critical Review of the Clinical Evidence, Effects on the Vaginal Ecosystem and Safety
Year: 2026
Type: preprint
Abstract: Oak galls, known in Malaysia and Indonesia as manjakani, are traditionally used for vaginal discharge, laxity and postpartum care, and are widely sold in feminine washes and tightening products. A 2023 systematic review of oak gall phytochemistry and bioactivity did not address these uses. This review examines the clinical evidence for oak gall in female genital conditions, its likely effects on the vaginal ecosystem, and its safety by route of use. One double-blind randomised trial found similar short-term cure of bacterial vaginosis with an oak gall cream and metronidazole gel (82.1% versus 87.5%), but it was not designed to show equivalence and did not assess recurrence. No trial supports tightening claims. Gall extracts inhibit Lactobacillus acidophilus at the same concentrations as pathogens, regular douching increases bacterial vaginosis risk, and intravaginal tightening products have been associated with HIV acquisition. Repeated oral dosing of a gall extract caused organ lesions and reduced thyroid hormones in rats at 500 mg/kg/day, and tannic acid absorbed through damaged tissue has caused fatal liver necrosis. Reported tannic acid contents above 1000 mg/g also show that quantification needs validation. Oak gall products should be limited to external use until microbiota, irritation and recurrence data are available.
Source: Preprints.org
Author: Kuak Ping Ng
Language: English
Topic: Medicinal Plant Research
Subfield: Plant Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7224255137