Anti-retroviral drugs used to treat HIV/Aids are being bought and smoked by teenagers in South Africa to get high.
Reports suggest that the drugs are being sold by patients and even healthcare staff for money.
Schoolchildren have been spotted smoking the drugs, which are ground into powder and sometimes mixed with painkillers or marijuana.
Aids patients themselves have been found smoking the drugs instead of taking them as prescribed.
Anti-retrovirals are used to boost the immune system of people with HIV and to suppress the virus in the blood.
"I couldn't believe it. I was shocked at first, these were school boys in their school uniforms," documentary-maker Tooli Nhlapo told the BBC World Service's Outlook programme.
"They take a pill and grind it, until it is a powder. Some also mix it with painkillers and others mix it with marijuana," said Ms Nhlapo. "They showed me how they roll it and smoke it."
Hallucinogenic
When the South African Broadcasting Corporation documentary-maker first investigated the story, she was told to wait until school finished, so she could actually see how young some of the users were.

The pills are crushed and mixed with other ingredients, like marijuana
"I thought I was going to go to a tavern and see older drug addicts doing this, but I was shocked when I saw school children," she said.
"One who spoke to me very frankly was only 15 and the oldest person I spoke to was 21, but it's mainly youngsters, teenagers."
Smoking the pills has a hallucinogenic and relaxing effect.
"When I asked them why they like doing it, they said it helps them relax and forget about their problems," said Ms Nhlapo.
"When you look at them, just a few seconds after taking it, they are in another world," she added.
The children do not know where they are and they stop making sense.
The young users that Ms Nhlapo spoke to get access to these drugs from HIV patients or healthcare workers.
They know when the individual patients go to collect the drugs and buy them, or if they do not have any money, they steal them.

"When I was doing the story, many HIV patients were complaining that they don't get the drugs and that queues are long and it was taking a long time to access them," said Ms Nhlapo.
Widespread problem
Dr Kas Kasongo, who advises on an anti-retroviral drugs panel in South Africa, feels that there needs to be some measure of accountability or a system to be able to track the usage of drugs.
"We need pharmacists and good administrators but again it is a social problem," he said.
"I don't think our role as doctors should be to just dish out drugs. We have to make sure that these drugs are taken as recommended."
When Ms Nhlapo first came across this new drug phenomenon, she thought it was just happening in one area, among a small group of people.
"I went back to the township and then I discovered that it was something that was known in the entire township," she said.
It had now become a national problem in South Africa, she added.
Dr Kasongo continued: "Not taking the optimum dose as recommended will not suppress the virus and the CD4 count will be destroyed massively and that's what we are trying to prevent by giving anti-retroviral medication."
Side-effects
Most anti-retroviral drugs can be given to both children and adults, Dr Kasongo said. But there was one exception.
"There is one that is being abused that should only be used above the age of three or four years," he added.
"Remember we are giving anti-retroviral drugs to those infected with HIV, who will eventually develop Aids.
"So, people who are healthy, that are taking this medication are exposing themselves to potential side-effects of these drugs," he added.

No matter how high they are, they do not tell you who is giving them the drugs
HIV patients are exposing themselves to huge risks by not taking the prescribed drugs as they should, he warned.
"We don't have more than 20 anti-retroviral drugs on the market and remember, they have to be used in a cocktail of at least three or four," said Dr Kasongo.
"Therefore, abusing a particular drug, whichever it is, is a concern because it can give rise to resistance to drugs within that same group," he added.
Dr Kasongo stressed that it will take a huge team effort, involving the government, social workers and education authorities to combat the problem.
"It is well organised, no matter how high they are, they do not tell you who is giving them the drugs," said Ms Nhlapo.