False. Worked in a hospital and two people I knew ended up in the ER at different times. You could argue they should have went to a psychiatric facility instead of the ER but they would have been evaluated medically first there anyway. They are safer than opiates and other hard drugs for sure. But there are definitely risks especially for those psychologically compromised, a condition commonly found in westerners in Thailand. I remember people laughing and giggling while chugging mushroom tea like it was a big joke and telling them your going to be very sorry in about three hours. And they were.
Also see "Adverse experiences resulting in emergency medical treatment seeking following the use of magic mushrooms"
"The most prevalent symptoms were psychological in nature, namely anxiety/panic and paranoia/suspiciousness. These are consistent with previous reports of the nature of adverse reactions to psilocybin and other psychedelics and have been discussed in depth elsewhere (Barrett et al., 2016; Van Amsterdam et al., 2011). However, a number of concerning physiological symptoms also occurred; passing out or going unconscious, difficulty breathing and seizures were reported by 37%, 32% and 26%, respectively. While difficulty breathing is commonly related to panic and anxiety, aetiology behind the two others is less clear. Rapid changes in blood pressure induced either directly by the drug or by psychological reactions, as well as dehydration or undernutrition are plausible triggers for losing consciousness under psilocybin"