A teenager said she was left crying in a classroom as children were taught incorrect information about HIV.
She is one of about 20 children aged 18 and under living in Wales with the disease.
Jessica - not her real name - told BBC Wales Live she wept as jokes about the condition went unchallenged.
Campaigners said there should be a new education drive about HIV and how medicine has revolutionised treatments.
Jessica said myths about the disease persist - that touching or sharing a cup or even a hat can pass on the virus, and people with HIV will die of AIDS.
But drugs introduced more than 20 years ago mean those living with HIV can control the infection so effectively it is undetectable and cannot be passed on to another person, even through sexual activity.
Antiviral treatments used since 1996 also mean those with the virus will enjoy the same life expectancy as those without the condition.
Jessica said she sat through lessons in school where incorrect information was shared with other pupils and jokes about the illness were allowed.
"I was sat at the back of that classroom and I cried my eyes out. But I had to hide it at the same time, because these were people that I wanted to potentially tell," she said.
"I've never been so shocked and ashamed of myself in my entire life - I shouldn't have been upset in that way."
Consultant paediatrician Dr Jennifer Evans said this was not a surprise.
"If people have a serious diagnosis of cancer there's huge amount of sympathy - this diagnosis is still met with a lot of suspicion," she said.
"That transmits itself into feeling bad about yourself."
Jessica agreed: "If there was less stigma, I would 100% be the person out there talking to all my friends.
"I feel like those conversations would've been a lot easier if in school it was educated properly."
Abi Carter, an participation officer with the charity Chiva - Children's HIV Association - said the lack of education about the disease could hold people back.
"We need another public information campaign about HIV, which is updated with all the revolutions that have happened in medicine over the last 20 to 30 years. There's a lot of misinformed people out there.
"It's time that we really busted some of these myths."
A Welsh Government official said the new education curriculum included guidance on learning how to find information from trusted sources to inform decisions and "challenging harmful social influences", including stigma.
"We recognise how HIV has changed in terms of risk and disease profile in the last decade and think it is important that teachers should have the most up-to-date information on HIV available to them."
BBC Wales Live, BBC One Wales, 22:30 GMT on 30 October or on BBC iPlayer
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