Australia's Therapeutic Goods Administration (TGA) on Friday said it was approving the psychedelic substances MDMA and psilocybin for medical use.
From July, psychiatrists will be able to prescribe the two substances — better known as ecstasy and magic mushrooms — to treat depression and post-traumatic stress.
Why have experts made the decision?
The Australian drugs watchdog said it had found "sufficient evidence for potential benefits in certain patients."
"The decision acknowledges the current lack of options for patients with specific treatment-resistant mental illnesses. It means that psilocybin and MDMA can be used therapeutically in a controlled medical setting.
"However, patients may be vulnerable during psychedelic-assisted psychotherapy, requiring controls to protect these patients," the TGA said.
The TGA said it would allow practitioners to prescribe the drugs only after individual approval by a human research ethics committee.
"Prescribing will be limited to psychiatrists, given their specialized qualifications and expertise to diagnose and treat patients with serious mental health conditions, with therapies that are not yet well established," the watchdog said.
While authorities will list the two ingredients as controlled drugs for medical use, they will remain prohibited substances for all other purposes — restricting their use to clinical trials.
Advocates of psilocybin and MDMA hope doctors might one day use them to treat alcohol dependence, obsessive-compulsive disorder, and eating disorders.
"If sufficient new evidence emerges that these substances will be beneficial in treating other conditions, the TGA can consider applications to make further amendments," the TGA said.
Mike Musker, a mental health and suicide prevention researcher at the University of South Australia, told the AFP news agency that the move had been long-awaited. He said the two drugs "reduce inhibitions" and could allow people to process difficult images and memories.
"There are many people in the community experiencing PTSD [post-traumatic stress disorder] and depression, particularly army veterans and people who have worked in emergency services, where standard psychiatric drugs have not worked and offer no relief," said Musker.
Two drugs, different histories
While indigenous people have used psychedelics for millennia, Western researchers only began to seriously look at their effects and potential medical uses in the middle of the last century.
Psilocybin is a naturally occurring compound produced by more than 200 species of fungi.
Although biologically inactive, psilocybin rapidly metabolizes to psilocin, which has mind-changing effects similar to LSD.
Images on prehistoric rock paintings suggest that humans used psilocybin long before recorded history.
MDMA, meanwhile, was initially synthesized in 1912 by the German pharmaceutical company Merck as part of work to develop substances that stopped abnormal bleeding.
Other researchers, including the US military, became interested in its use as a psychedelic agent only decades later. MDMA became better known as the popular recreational drug ecstasy in the 1980s and 1990s, although it was possibly used by thrillseekers as early as the 1960s.
