It seems that some women will stop at nothing in their pursuit of holistic rejuvenation. Ground-up wasp nests, also known as oak gall powder or Manjakani, are being touted as the latest treatment to tighten the vagina and rid it of any odours, and doctors are concerned about their effects.

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Sold on sites like Amazon and Etsy, oak galls (or oak apples) are the bulbous tree growths that result from wasps laying larvae in branches. Because the tree regards the larvae as an irritant, it naturally creates a hard shell around it and the little worms inside feed off the growth until they can break free. Some holistic practitioners believe that once the oak galls are ground up and mixed into a paste or boiled and used as a vaginal wash, their astringent properties will tighten and firm the muscles of the vagina, and ultimately improve elasticity, according to Popular Science.

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But doctors like Jen Gunter, a Canadian-born gynaecologist who practices in San Francisco, are eager to share the dangers of oak galls. In a recent blog post, Gunter explained that the pitfalls of engaging in the practice can range from mild to very hazardous.

“This product follows the same dangerous pathway of other ‘traditional’ vaginal practices, meaning tightening and drying the vagina which is both medically and sexually (for women anyway) undesirable,” she writes. “Drying the vaginal mucosa increases the risk of abrasions during sex (not good) and destroys the protective mucous layer (not good).”

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The use of oak galls dates back centuries, when women in India, Malaysia, China and parts of the Middle East believed their antibacterial properties would help them treat postpartum bacterial infections.

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“That is far from what women should be placing in their vaginas and should not be a practice that is considered helpful or therapeutic,” Dr. Jessica Shepherd, assistant professor of clinical obstetrics and gynaecology at the University of Illinois College of Medicine at Chicago, said to Women’s Health magazine.

In addition to the bizarre vaginal practice, the Etsy listing says oak galls can also be used as a dental powder and a remedy for toothaches or gingivitis, as well as a treatment for acne and enlarged pores.

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It’s also touted to help “heal episiotomy cuts” — the vulval opening that can be surgically enlarged to facilitate childbirth — although it reportedly “burns” when applied.

“Here’s a pro-tip: if something burns when you apply it to the vagina it is generally bad for the vagina,” Gunter writes. “So don’t put dried up wasp’s nest in your vagina. I feel pretty confident in offering that up as medical advice.”

This is just another in a long list of “healing” holistic practices that have been promoted by celebrities over the last few years, from Shailene Woodley’s vaginal sunbathing to Tamera Mowry’s vaginal steaming, and of course, Gwyneth Paltrow’s jade eggs, which purportedly also help to improve vaginal muscle tone.