haarlem oil haarlem oil haarlem oil (dutch: haarlemmerolie), also called medicamentum gratia probatum, is a dietary supplement. the potion is a mixture of sulfur, herbs and terebinth oil. it is produced in haarlem, netherlands. haarlem oil in 2013 old german advertisement for haarlem oil as cure for stomach, gut, liver and bile sickness. it was invented in 1696 by claes tilly and was marketed as a cure for many ailments. the word haarlemmerolie (with a lowercase 'h') is now used in dutch to indicate a fix for all problems. for example: "lowering taxes will be like haarlemmerolie for the economy". this is also used sarcastically. benefits to race horses - - greatly improves the urinary system and removes most toxins in the horse's system. - haarlem oil guarantees against infections, such as respiratory, urinary, biliary, and intestinal. - naturally stimulates the horse's own hormone secretions without side effects. - helps assist the rapid recovery process after the horse competes. - fights any and all arthritic actions.