The death of a New Zealander during a Peruvian ritual involving a hallucinogenic concoction has raised concerns about the ancient practice turned tourist attraction.
Matthew Dawson-Clarke went to Peru in September 2015 to try ayahuasca - thought to be one of the world's strongest hallucinogens - but died at the retreat where the ceremonies took place.
His family didn't hear about his death from official sources - a tourist who was with the 24-year-old called his mother Lyndie three days later to offer her condolences.
Ms Dawson-Clarke spoke for the first time about the family's experience to ABC's Foreign Correspondent journalist Hamish Macdonald.
Mr Macdonald told the AM Show the call sparked a "fact-finding mission" for the family, with their search for justice ultimately unlikely to be successful.
What is ayahuasca?
Ayahuasca is a vine which grows mainly in the Amazon and as a ceremony is an ancient Amazonian tradition.
"The ayahuasca vine is a purgative which makes you vomit, it makes you go to the toilet pretty aggressively it must be said," Mr Macdonald says.
The vine is brewed in a tea with a leaf which contains DMT - a psychoactive substance making it "one of the world's most powerful hallucinogens".
"Locally in Peru, they don't call it a drug; they call it a medicine. They believe it has immense healing properties. Many of those we met in the Amazon spoke incredibly highly of ayahuasca as an experience."
And it's an experience which is becoming more of an attraction for tourists, with the remote city of Iquitos being a major launching point for the retreats hours into the Amazon jungle.
"What we saw were people coming for all sorts of reasons - young, old, heacy drug users, non-drug users, people who wanted spiritual growth, people who wanted help with their alcoholism or heroin addictions," Mr Macdonald says.
The ceremony itself is "pretty full on".
"It happens in pitch darkness and you hear the shaman singing songs, you hear them toasting the ritual and you sit back and listen to them vomit and go to the toilet for four, five, six hours. It is not a particularly pleasant thing to watch, but the people who do it seem to think it's great."
It's also an experience which has been marketed by Western tour operators, known locally as 'gringo-shamans' who have a major interest in protecting the money-spinning attraction.
Mr Dawson-Clarke had researched ayahuasca extensively and "told his family all about it".
"[He] wanted spiritual growth, he wanted to have the experience, but Matt is among those whose experience did not end well."
Five others have been known to have died either at, during or following the ritual since Mr Dawson-Clarke's death.
It is also entering the mainstream drug world, with celebrities such as Sting and Lindsay Lohan talking openly about their experiences and even a mention in the Absolutely Fabulous TV show.
The death of Matthew Dawson-Clarke
But it wasn't the ayahuasca which likely killed Mr Dawson-Clarke.
While he'd partaken in the ceremony the previous night, it wasn't until 7am the next morning when he was given a tobacco tea used as a cleansing ritual leading up to the ayahuasca ceremony held at night.
"Within 15 minutes , according to multiple sources there, he said he felt sick, he even mentioned he thought he'd be poisoned," Mr Macdonald says.
But it wasn't until 5pm until anyone at the retreat did anything about it - and it wasn't the shaman or the staff - it was fellow tourists who decided to get him on a motorbike, along the Amazon River and back to a hospital in Iquitos.
But it was too late.
A coronial inquest in New Zealand into Mr Dawson-Clarke's death was inconclusive in its interim findings, Foreign Correspondent reports.
The search for justice
Mr Dawson-Clarke's family lodged an official complaint after the initial investigation seemed to be closed "too quickly and without seeming to follow the basic ground work that you'd expect them to do".
Many on the retreat hadn't been interviewed and neither had the tour operator. It was only a few weeks ago when Mr Macdonald and his crew were in Peru that the shaman Don Lucha, who served Mr Dawson-Clarke the tobacco tea, was formally questioned by a prosecutor.
"I think it's a more complex picture than just the ancient Amazonian ritual and people turning up to engage with that, I think there are people who are really cashing in, and making a lot of money out of this and have a great deal of vested interested in ensuring no questions are asked," Mr Macdonald says.
Tour operator and expat Briton Andy Metcalfe told Foreign Correspondent the risk of ayahuasca were relatively low and denied any responsibility for Mr Dawson-Clarke's death.
"We had well over 1000 people on retreats before Matt came along and no incidents whatsoever."
However, he accepted "maybe we were complacent".
Mr Macdonald says while the family's search for justice may be difficult, it isn't impossible.
"There is a chance that justice will be served, but this is just the first step in a very long process. Even if the trial went ahead, even if there was a conviction it wouldn't be along jail term."
But Mr Macdonald says the family's message to others was clear - they don't want to stop people from living their lives, but urges people to be aware of the risks of what they intend to do.