Students say they have been left feeling embarrassed and anxious due to "baffling" school toilet restrictions.
Holly, from Pentyrch, Cardiff, said she would frequently be denied permission to go to the toilet during class, or struggle to find one that was not "locked off", which contributed to her decision to be home-schooled.
"I don't understand why, it's a normal, natural human thing," she said.
It comes after a UK-wide survey found 65% of students were unable to access toilets at their school freely at any time.
Cardiff council said it acknowledged the challenges faced by schools but was committed to working with them to find solutions for pupils to access toilets when needed.
Holly, who is autistic and has attention deficit hyperactivity disorder (ADHD) and sensory processing disorder, previously attended Radyr Comprehensive School but began being home-schooled with an online tutor in January 2024.
The 15-year-old said toilet rules were a "major contributor" in the decision.
"Sometimes we would have to ask in front of the class and we would be denied, sometimes we would have to tell them why we needed to go to the toilet," she said.
"It was hugely embarrassing, you would toy with yourself [as to] whether you had the confidence to put up your hand and ask. It's a big feeling of potential judgement."
Holly said she and her friends had "bled through our underwear", adding: "One of my friends bled through onto a chair and had to do a walk of shame. It was one of her first periods and people made fun of her for weeks."
She said some toilets were "locked off" during class time, to stop pupils going to certain parts of the school.
