A top doctor is warning against a bizarre trend that suggests ground-up wasp nests will help tighten the vagina.

While some natural ingredients are commonly used and endorsed for home remedies, Canadian gynecologist Jen Gunter is warning against one in particular.

Some online retailers, including on Etsy, have been selling oak galls - nests which house wasp eggs - which, they say, should be ground into a paste for 'vaginal rejuvenation'.

Oak galls are formed when a gall wasp lays eggs in a tree's leaf buds and the larva will then develop while inside the gall.

The substance, retailers claim, will restore the uterine wall after childbirth, heal an episiotomy cut and also clean out the vagina.

But Dr Gunter has spoken out on her blog, insisting that it is not recommended and could lead to a slew of side effects - including painful sex, a lack of healthy bacteria and an increased risk of contracting HIV.

Online Etsy shop HeritageHealthShop (pictured) was selling the oak galls online, claiming they could tighten the vaginal wall and be used for cleaning out the vagina

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Dr Gunter slammed the practice calling it 'dangerous' on her blog.

She said: 'This product follows the same dangerous pathway of other 'traditional' vaginal practices.

'Drying the vaginal mucosa increases the risk of abrasions during sex (not good) and destroys the protective mucous layer (not good).

'It could also wreak havoc with the good bacteria. In addition to causing pain during sex it can increase the risk of HIV transmission. This is a dangerous practice with real potential to harm.'

Health website the Female Renewal Solution claims that oak gall can help prevent cervical cancer and is 'all you need' to make the vagina 'tighter instantly and overnight.'

Etsy retailer HeritageHealthShop hawked the product by citing South East Asia medicine claims that the galls could improve sex lives and be used on cuts.

The page, which has since sold out of the galls, suggested grinding the balls into a paste to be applied to episiotomy cuts, which is a surgical cut in the muscular area between the vagina and the anus.

It used to be routinely done before delivery to enlarge the vaginal opening to prevent the vagina from tearing during childbirth.

HeritageHealthShop does warn that the paste will hurt but said it was due to the 'galls' powerful astringent'.

Dr Gunter said: 'Here's a pro-tip, if something burns when you apply it to the vagina it is generally bad for the vagina.'

This isn't the first time Dr Gunter has cautioned against products claiming to clean, dry or tighten the vagina.

Oak galls are formed when a gall wasp lays eggs in a tree's leaf buds and the larva will then develop while inside the gall. Pictured: Oak galls on a tree (left) and gall wasp larva (right)

The gall paste was being promoted as traditional South East Asia medicine and could improve sex lives. Pictured: A fully grown gall wasp

Dr Gunter also warned against using herbal 'womb detox' products that claim to flush out toxins and tighten the womb. These products can lead to toxic shock syndrome. Pictured: Florida-based firm Embrace Pangaea's perfumed herb balls

Last year she warned women not to use herbal 'womb detox' products because they were risking health problems including toxic shock syndrome.

The Herbal Womb Detox Pearls are still being sold worldwide by Florida-based firm Embrace Pangaea.

The site claims the products can help with conditions including endometriosis, ovarian cysts, thrush and fibroids.

Women are directed to use the bags of perfumed herbs three at a time, for 72 hours.

The pearls claim to 'cleanse the womb and return it to a balance[d] state' by flushing out toxins.

The company claims that by tightening the womb, the vaginal canal will shrink and 'can result in heightened sexual pleasure.'

The website warns virgins, pregnant women or those breast-feeding against using the product.

Dr Gunter said the 'pearls' were not only ineffective and inserting anything into the vagina for too long was 'dangerous and smelly.'

Describing the vagina as like a 'self-cleaning oven,' she explained how inserting herbs is likely to interfere with its natural balance, damaging the good bacteria, or lactobacilli and irritating the lining, increasing the risk of getting an infection.