The body of a British teenager has been found by the road in a Colombian forest, after he took part in a "shaman experience" advertised for tourists.

His family have said that Henry Miller, 19, from Kingsdown in Bristol, took part in a local tribal ritual, drinking a herbal concoction known as yagé and apparently suffering a fatal reaction to the hallucinogenic infusion.

Reports suggest that Miller was with a group of foreign tourists – all of whom had paid $50 (£36) for the experience and who drank the brew together – but who were ushered back to their lodgings when Miller took ill with the assurance that the tribespeople were looking after him.

His body was found dumped by a road near the southern city of Mocoa, close to the border with Ecuador and on the edge of the Amazonian basin.

David and Elizabeth Miller said their youngest son had been travelling around South America for several months and was due to start at university in September. He had arrived in Mocoa last Sunday. In a statement the family said: "In the last 48 hours we received the exceptionally sad news that our son Henry has died while travelling in Colombia.

"We are being informed of the circumstances through the Foreign Office.

"He was in the remote Putumayo region. We understand that he took part in a local tribal ritual recommended by the hostel that he was staying at. The ritual involves a drink made from local plant infusions.

"We are awaiting further information from the Foreign Office but it is likely that a reaction to this drink was the cause."

Miller's older brother Freddie added: "Henry was an adventurous person who travelled extensively. He was polite, popular with a great sense of humour and was very much loved by his family and his many friends.

"We hope we can all be given the time and space to come to terms with what has happened and to grieve for our son and brother."

The Foreign Office said it was "aware of the death of a British national in Colombia", and was assisting his family "at this very difficult time".

Yagé, also known as ayahuasca, is legal and is made by infusing leaves of several different plants. It has been used for centuries by native people in South America for healing and spiritual purposes. It is said to bring on visions, but it can also cause vomiting, diarrhoea and psychological distress and is recommended to be taken only in the presence of a respected shaman. The effects of the drug were documented by writer William Burroughs in his book The Yage Letters, in which he wrote to poet Allen Ginsberg of his mind-altering experiences.