Writing in the Journal of Psychopharmacology (which he edits), University of Bristol neuropsychopharmacologist David Nutt, who chairs the British Advisory Council on the Misuse of Drugs (ACMD), sounds the alarm about the dangers of equasy:
What is equasy? It is an addiction that produces the release of adrenaline and endorphins and which is used by many millions of people in the UK including children and young people. The harmful consequences are well established—about 10 people a year die of it and many more suffer permanent neurological damage as had my patient. It has been estimated that there is a serious adverse event every 350 exposures and these are unpredictable, though more likely in experienced users who take more risks with equasy. It is also associated with over 100 road traffic accidents per year—often with deaths. Equasy leads to gatherings of users that often are associated with these groups engaging in violent conduct.
Dependence, as defined by the need to continue to use, has been accepted by the courts in divorce settlements. Based on these harms, it seems likely that the ACMD would recommend control under the MDAct perhaps as a class A drug given it appears more harmful than ecstasy.
Have you worked out what equasy is yet? It stands for Equine Addiction Syndrome, a condition characterised by gaining pleasure from horses and being prepared to countenance the consequences especially the harms from falling off/under the horse. I suspect most people will be surprised that riding is such a dangerous activity. The data are quite startling—people die and are permanently damaged from falling—with neck and spine fracture leading to permanent spinal injury (Silver and Parry, 1991; Silver 2002). Head injury is four times more common though often less obvious and is the usual cause of death. In the USA, approximately 11,500 cases of traumatic head injury a year are due to riding (Thomas, et al., 2006), and we can presume a proportionate number in the UK. Personality change, reduced motor function and even early onset Parkinson's disease are well recognised especially in rural clinical practices where horse riding is very common. In some shire counties, it has been estimated that riding causes more head injury than road traffic accidents.
The whole journal article, including a table comparing equasy to Ecstasy (MDMA) using a nine-point scale designed to measure drug-related harm, is here (PDF).
Speaking of horses and highs, check out Cracked's list of "7 Species That Get High More Than We Do," featuring locoweeded horses, drunken elephants, and lichen-licking sheep.
[Thanks to Mattias Svensson for the tip.]