Australians suffering from treatment-resistant mental health problems will soon have access to psychedelic therapies including MDMA and psilocybin, commonly known as ecstasy and magic mushrooms.

The Therapeutic Goods Administration (TGA) flagged in February that Australia will be the first country to allow psychiatrists to prescribe MDMA for the treatment of post-traumatic stress disorder (PTSD) and psilocybin for treatment-resistant depression from July.

They are the only two conditions where there is sufficient evidence for potential benefits, the TGA said.

The news has been welcomed by many but some experts are concerned the rollout could face hurdles, particularly the prohibitive cost to patients of about $10,000 for treatment.

Professor Colleen Loo is a clinical psychiatrist and researcher at UNSW Sydney and the Black Dog Institute, and says other concerns about the treatment include the potential for extreme mood swings.

She has worked in the field for years and is involved in two clinical trials for psilocybin, and established the first ketamine randomised controlled trials in Australia in 2016.

"With ketamine, you can be catapulted from being severely depressed to being completely well in one day," she said on Monday.

"I've never seen anything like it. It's an incredibly powerful treatment, both in terms of how effective it is and how rapidly it works," Prof Loo said.

However, the cost will also be a prohibitive barrier for many.

"It will be quite expensive - $10,000 or more for a treatment course," she said.

"People who are desperate will pay that."

The clinical study of psychedelic therapies received strong support in the 1940s and 1950s but funding decreased when the drugs became synonymous with the party scene from the 1960s onwards, and government grants dried up.

In the 2000s research into psychedelics slowly started up again with a focus on the potential to treat patients with mental illnesses who did not benefit from existing therapies.