Louise Hosie, 36, from Livingstone, Scotland, found lube in daughter's pocket.
Summer, five, had mistaken bottle of lube from Ann Summers for hand sanitiser.
Young girl had described it as 'hot and smooth' and shared it with her friends.
Mother of three said she was embarrassed but also saw the funny side of it all.
A mother was shocked when she discovered her five-year-old daughter had taken her lube to school thinking it was a bottle of hand sanitiser.
Louise Hosie, 36, from Livingstone, Scotland, found the bottle in her daughter's school coat as she emptied the pockets to load into the washing machine.
Five-year-old Summer saw the Ann Summers' logo on the intimate 'Heat Wave' lotion and thought it meant it was hers, The Sun reports.
When mum-of-three Louise quizzed her daughter she discovered that she had been using it as hand sanitiser and had even shared it with her friends.
Louise said: 'I'd done a balloon pop with Ann Summers where the lady goes live online and she pops it and you get your prize.
'Mine was two bottles of lube and some perfume, but I'd just left it in the box, it hadn't been touched.
'I went to wash Summer's school jacket the other day and I was emptying out her pockets and I found it.
'I was like 'oh my god, why have you got that?' and she said 'it's for my hands, for the germs.'
Summer had innocently wanted to take the hand sanitiser into school to stay safe during the pandemic but had mistakenly picked up the bottle of lube instead.
Louise adds: 'I had to tell her 'this is for mummy, this needs to go in the cupboard.'
'And then I asked her if she'd used it with her friends and she said yes. I was so embarrassed.'
Speaking about the incident to The Sun Louise said Summer told her she 'liked it because it felt hot and smooth'.
Louise, who works in retail, has no idea how long Summer had been using the lube, but thinks it can't have been more than a couple of days as none of her teachers spotted the blunder.
'The prospect of doing the school run after half term has crossed my mind, I'll be pretty embarrassed to face her teachers,' Louise added.
'Loads of friends and family have messaged me to laugh about it, they've started calling me Lubey Lou.'
Louise says this is typical of Summer as the youngster spent lockdown playing pranks on her older brothers, Liam, 16 and Shaun, 14.
She went on: 'She'd seen her brothers doing TikTok videos during lockdown and she ran up behind Liam and cracked an egg on his head.
'Luckily they saw the funny side, Summer's always up to mischief.'
The mother of three plans to remind Summer of her mistake when she turns 18.