Caution: This episode contains references to drug use. 

You may know it as an illegal party drug. But there's growing research to suggest that psychedelic drugs could be used , in a clinical setting, as treatments for depression, addiction and PTSD. 

Some clinical trials seem to show that these substances, when combined with therapy, can be effective for some of those who find antidepressants and other forms of therapy unhelpful. 

But this is a drug that has had proven negative-side effects such as addiction and bladder issues. 

Today, we look at one particular drug, ketamine, as the UK's first ketamine-assisted psychotherapy clinic prepares to open, and our reporter Keme Nzerem meets one person who's found this treatment transformative.

Could this clinic mark a shift in the way we view psychedelics? Or is it an expensive, under-researched and unproven experiment? 

If you’ve been affected by any of the issues in this episode, you can find information and support on our website: channel4.com/support

Sources: BBC News, ITV News, PBS News Hour, ABC News.