Supermarket staff were mystified when a cream for baby’s bottom began selling like hot cakes.
Then they discovered the reason - mums were putting it on their own faces.
At £2.49 a pot, Waitrose’s own-label Baby Bottom Butter is only a fraction of the cost of designer products.
And its new-found fans claim it is the answer to their prayers.
The buying frenzy began after it was given glowing endorsements on parenting websites.
One contributor to mumsnet.com wrote: “I can’t even remember what made me put it on my face one day but OMG - it is fab.
“I have been using it constantly for 2 weeks now and my skin now has the smoothest texture, which I don’t think it’s had since prepubescence.
“And it makes my foundation look super dewy and youthful too. It is SO much better than all the expensive face creams I have tried - including Creme de la Mer.”
While some complained that it left their skin spotty or greasy, another mum gushed: “I have taken to putting it on twice a day, I am eighteen again!”
And a third added: “Really really impressed with how plumped and smooth it makes my skin look, especially around the eyes”.
The butter is free from artificial chemicals and contains olive oil, camomile - for nappy rash - and lavender.
Waitrose says it has seen sales of “natural” baby toiletries rise by 38 per cent after it removed parabens, petrochemicals and colours from its own-label products.
Sales of Baby Bottom Butter doubled to around 30,000 tubs in the first part of this year, taking its Hampshire-based supplier by surprise and leading to shortages on the shelves.
However, women keen to try it have been assured that new stock should be on sale from Monday.
Waitrose’s baby care buyer Jo Maclaine said: “It seems that the botty butter gives softer cheeks wherever they are.
“The feedback we have had has been amazing and proof that looking good does not have to cost the Earth.”
Of course it is not the first time an unlikely item becoming the new musthave beauty product.
Haemorrhoid ointment has also been championed as face cream by the likes of actress Sandra Bullock.
However cosmetic surgery expert Dr Patrick Bowler, who appeared on the TV programme Ten Years Younger, said he was sceptical about the supposed benefits of Baby Bottom Butter.
“The women buying this may think it will make their faces as smooth as a baby’s bottom, but the truth is that while it’s likely to be quite a good moisturiser there’s really nothing extraordinary about it.
“And if they’re buying it because they have babies, they’re likely to be quite young themselves, which means they’ll have pretty good skin anyway.”