(CNN) "Magic mushrooms" may have moved one step closer to becoming a treatment for depression.

The active ingredient in psychedelic mushrooms is called psilocybin -- and a new British study suggests it could safely be used to treat depression when other drugs have failed, offering hope to millions of patients worldwide.

The study, conducted by King's College London and mental healthcare company Compass Pathways, administered psilocybin to 89 healthy adult volunteers.

The study compared the effects of 10mg and 25mg doses of psilocybin, and a placebo.

There were "no serious adverse events" and "no negative effects" on cognitive and emotional function among the volunteers that took psilocybin, according to a Compass Pathways press release . Instead, the volunteers experienced "changes in sensory perception and positive mood alteration" -- typical effects of psychedelic drugs.