Australia has become the first country in the world to legalise the use of psychedelics to treat some mental health conditions.
According to the BBC Approved psychiatrists can now prescribe MDMA to those suffering post-traumatic stress disorder and magic mushrooms for some types of depression.
The controversial move has been hailed as a game-changer by many scientists and mental health experts.
However, others say the move has been too hasty and should not be over-hyped.
Experts say there is still the risk of a "bad trip", which is when the user has an unpleasant experience while under the influence of drugs.
And the therapy comes at a cost, with Australian media reporting one course could cost tens of thousands of dollars.
MDMA - also known as the party drug ecstasy - is a synthetic drug that acts as a hallucinogen. It increases the user's energy levels, sensory experiences and distorts their sense of time.
Magic mushrooms, which grow naturally, also have hallucinogenic effects due to the active compound psilocybin.
While Australia is the first country in the world to regulate the drugs as medications, clinical trials are also underway in the US, Canada and Israel.
Under the new regulations which became official in Australia on 1 July, approved psychiatrists can prescribe MDMA for post-traumatic stress disorder (PTSD) and psilocybin for depression that has resisted other treatments.
Use of the psychedelics would be carefully monitored and not a case of "take a pill and go away", said Dr Mike Musker, a mental health researcher at the University of South Australia.
Describing the move as a "game-changer", he told AFP news agency that, in the case of MDMA for example, the patient would likely have three treatments over five to eight weeks. Each treatment would last about eight hours, with the therapist staying with the patient the whole time.
Patients should not expect a miracle cure, however.
"I have read about stories where people have had what you call bad trips, or actually they've re-experienced their trauma, and so we've got to take great caution," Dr Musker said.
Professor Susan Rossell, a cognitive neuropsychologist at Melbourne's Swinburne University said that while psychedelics certainly had the potential for therapeutic use, the move had come about too quickly.
"When you look at interventions... for any other kind of disease, whether it's cardiovascular disease or cancer, you cannot get a drug to market as quickly as this has been done," she told AFP.
Prof Rossell, who is leading Australia's biggest trial on the effects of psilocybin on depression, added that more research was needed to determine the long-term outcomes of the therapy.
Australia's Therapeutic Goods Administration (TGA) shocked many in the medical and science world in February when it reclassified MDMA and psilocybin so they could be used for therapeutic purposes.
It declared the drugs "relatively safe" when used in a "medically-controlled environment" for patients "with serious mental health conditions". Otherwise, both MDMA and psilocybin are illegal in Australia.
The TGA acknowledges that there are unknowns and inconclusive evidence, but says "there are promising signs" that controlled therapeutic use of the drugs may improve mental health for some people and that the "benefits for some patients... will outweigh the risks".
The regulator says there are currently no approved products that contain MDMA or psilocybin. However the reclassification means psychiatrists will be able to access and legally supply certain medicines that contain them, even if they have not been evaluated for safety or effectiveness.
