Ketamine and nitrous oxide are being used to help treat depression in new clinical trials in Australia.
Researchers believe the drugs, which are commonly dealt on the black market, can act as antidepressants.
Nitrous oxide, the chemical inside whipped cream canisters known to some as "nangs", has already shown promise as a rapid antidepressant and could be used to treat acutely suicidal patients.
The treatment would not be delivered through a canister, but in a clinical setting through a mask.
Ketamine, a horse tranquilliser that can cause psychedelic effects in humans, is being investigated by the University of NSW to determine if the drug will work as a long-term therapy for depression and "improve anxiety, suicidal ideation and health-related quality of life".
Online clinical trial matching platform HealthMatch has been recruiting for several mental health trials, and CEO Manuri Gunawardena says interest has been soaring as Australia steps out of lockdown.
The platform has noted a 544 per cent increase in applications for mental health trials, which Gunawardena said was a great sign not only for the medical industry but also for struggling patients.
"More than 80 per cent of clinical trials face delays or abandonment due to insufficient patient recruitment, and Covid has only further delayed these important medical breakthroughs.
"So to see such an uptick in clinical trials following the lift of restrictions – and in an area as prevalent as mental health, which affects millions of Australians – it's very rewarding.
"We've had a tremendous response from people looking to understand their potential treatment options. Not only are they being empowered to take control of their health, but they're also accessing cutting-edge research and contributing to our understanding of these conditions."
A Monash University study of more than 14,000 Australians showed two to three times as many people were reporting mild depression during the lockdown than usual, and 25 per cent of people were feeling moderate to severe symptoms of depression.
Those with significant symptoms were likely to be younger and less financially stable.