It's high time for psychedelic science.

Ever since drugs like psilocybin, the active ingredient in hallucinogenic mushrooms, appeared to help quell anxiety in cancer patients several years ago, the compounds have seen something of a resurgence of interest among scientists. Researchers are currently studying the potential of drugs ranging from ecstasy to ayahuasca to treat mental illnesses including depression and PTSD.

Investors are starting to join the bandwagon now, too. This week, Canadian entrepreneurs launched the world's first psychedelics-only venture firm, Business Insider reported exclusively. They hope to seed efforts to study the drugs' medical potential.

In the meantime, some psychedelic and semi-psychedelic drugs are turning into prescription medicines.

Last summer, federal regulators approved the first prescription drug made with marijuana, which many experts consider a psychedelic in high enough doses. Called Epidiolex, it is designed to treat rare forms of epilepsy. And this spring, regulators green-lit a drug inspired by ketamine and made by pharmaceutical giant Johnson & Johnson for severe forms of depression.

Other psychedelic drugs including ecstasy and psilocybin remain widely illegal, but that's beginning to change too.

In May, voters in Denver approved a measure to decriminalize psychedelic mushrooms, meaning that law enforcement would make policing their use a low priority. And recently, federal regulators assigned "breakthrough therapy" status to ecstasy, which could hasten its approval as a prescription drug for patients with PTSD.

A type of ecstasy might accelerate PTSD therapy

Researchers in October published the latest findings of a year-long study designed to assess if ecstasy or MDMA could play a role in treatment for PTSD. Their positive findings suggest that it could.

After the treatment, in which patients were given MDMA alongside traditional talk therapy and compared with a group that got the same treatment only using a placebo instead of the drug, some three-quarters of the participants no longer met the criteria for a PTSD diagnosis. In other words, their symptoms had resolved.

That's a significant result. One of the chief problems with current talk therapy is that even when patients are able to afford and access the treatment, they grow tired of the painful process of rehashing traumatic events and sometimes disappear for months on end, according to psychiatrist Julie Holland, who currently serves as a medical observer for the MDMA study.

Still, the treatment was tied to some unpleasant side effects including insomnia, tiredness, and headaches. The drug, which amps up the activity of chemical messengers involved in mood regulation, can be dangerous when used without medical supervision because it raises body temperature and blood pressure.

MDMA also recently received a key federal designation designed to hasten the research and approval process. Some experts believe the drug will be approved as early as 2021.

A compound in magic mushrooms is showing promise for anxiety

Researchers studying psilocybin, the main psychoactive ingredient in hallucinogenic mushrooms, have likened its quick effects on cancer patients to a "surgical intervention" for depression.

Brain scan studies suggest that depression ramps up the activity in brain circuits linked with negative emotions, and weakens the activity in circuits linked with positive ones. Psilocybin appears to restore balance to that system.

Two for-profit companies are currently leading the research in the space. The first, called Compass Pathways, is backed by entrepreneur Peter Thiel and has recently began its own clinical trials of magic mushrooms for depression.

The second, a biotech startup called Atai, is focused on financing more of the kind of research that Compass is doing. Atai has raisedfunds from investors like ex-hedge fund manager Mike Novogratz and Icelandic entrepreneur Thor Bjorgolfsson. In late March, the biotech said it raised another $43 million.

Some researchers have high hopes that a psilocybin-inspired drug will get approved within a decade. David Nutt, director of the neuropsychopharmacology unit at Imperial College London, told Business Insider last year that he believed psilocybin would become an "accepted treatment" for depression before 2027.

The first prescription drug made from marijuana won federal approval last summer

The first prescription drug made from marijuana won federal approval last summer.

Called Epidiolex, the drug is designed to treat two rare forms of childhood epilepsy using a cannabis compound called cannabidiol (or CBD).

British-based GW Pharmaceuticals makes the drug. It does not contain THC, the well-known psychoactive component of marijuana responsible for the drug's characteristic high.

The federal thumbs-up comes on the heels of several months of promising research results and a positive preliminary vote from the Food and Drug Administration this spring. Experts are hopeful that the approval will unleash a wave of new interest in the potential medical applications of CBD and other marijuana compounds to treat other psychiatric and neurological diseases.

Ketamine is inspiring novel treatments for depression

A widely used anesthetic that is also known as a party drug, ketamine was shown to have benefits as a rapid-fire antidepressant nearly a decade ago. Early studies suggested ketamine could help people who failed to respond to existing medications or were suicidal.

The authors of one paper called ketamine "the most important discovery in half a century."

In March, nasal spray called esketamine won approval from US regulators to treat severe forms of depression that don't respond to other medications. The brand name of the drug is Spravato, and it's taken as a nasal spray.

As opposed to existing antidepressants, ketamine appears to act on a brain mechanism that scientists have only recently begun to explore. Homing in on this channel appears to provide relief from depression that could arrive faster and work in more people than current drugs do.

Read more of our psychedelic medicine coverage:

This story was updated on June 14.