In his controversial memoir Spare, Harry admitted to regular drug-taking and describes how in 2015, while living in Nottingham Cottage in the grounds of Kensington Palace, he smoked marijuana.
On Saturday, he spoke to Dr Gabor Mate, author of The Myth Of Normal: Trauma, Illness & Healing In A Toxic Culture, in a live interview.
The pair covered topics including Harry's use of cocaine, marijuana and alcohol.
Fiona Spargo-Mabbs OBE, who founded the DSM Foundation in 2014 following the death of her 16-year-old son, said she feared Harry's comments sent out the wrong message about drugs to young people.
During the event Harry had said: “(Cocaine) didn’t do anything for me, it was more a social thing and gave me a sense of belonging for sure, I think it probably also made me feel different to the way I was feeling, which was kind of the point.
“Marijuana is different, that actually really did help me.”
Daniel Spargo-Mabbs died in 2014 after an accidental overdose of ecstasy while on a night out with friends.
His family felt that he hadn’t known enough to be able to make decisions that would keep him safe and set up a drug education charity to spare other families from going through what they had.
Mrs Spargo-Mabbs told ITV News: “It is understandable that when people are struggling, they look around for ways to cope.
"This is particularly true of young people, an increasing number of whom we know have been struggling with their mental health during and since Covid, yet who are unable to access support services because they are so stretched.
“Given this context, Prince Harry’s comments about using drugs as a way of dealing with past trauma could easily be misconstrued as being true across the board.
“The most recent NHS Digital data shows that for the first time, the second biggest reason both 11 and 13-year-olds gave for using drugs on the first occasion was to help them cope with their problems, so even at that young age they're getting a message from somewhere that controlled substances are going to help them to deal with difficult things."
Tickets for the livestreamed conversation between Harry and Dr Mate cost £17, plus a £2.12 fee for UK customers, and included a copy of Spare.
During the event, the duke spoke about the death of his mother, Diana, Princess of Wales, who died in a car crash in Paris in 1997 when the duke was just 12 years old. Harry also told of using psychedelics such as ayahuasca, which he described as giving him a "sense of relaxation, release, comfort, a lightness".
Harry said: “It was the cleaning of the windscreen, cleaning of the windshield, the removal of life’s filters just as much as on Instagram, these layers of filters.
“It removed it all for me and brought me a sense of relaxation, release, comfort, a lightness that I managed to hold on to for a period of time.
“I started doing it recreationally and then started to realise how good it was for me, I would say it is one of the fundamental parts of my life that changed me and helped me deal with the traumas and pains of the past.”
Mrs Spargo-Mabbs warned that anyone struggling with their mental health, particularly young people, should not look to drugs for a "quick fix" as this could increase the risk of dependency.
"While there is some really interesting work being done around the use of certain substances in a therapeutic context, particularly psychedelics, it is still very much at an experimental stage, and in a controlled, clinical environment," she said.
"There is also an increased risk of dependency in young people – this happens to around one in 10 who experiment with drugs – and more so in those who use drugs as a coping strategy.
"So it is vital that anyone who is struggling with their mental health doesn’t go for what might seem a quick fix, but instead looks for longer-term and evidence-based solutions such as talking therapies, and even reaching out to trusted family and friends.”
For more information and support on how to speak to young people about drug use, visit the DSM Foundation's website.
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