dose [LME] The Greek physician Galen (ad 129-c.199), used dosis, the Greek word for ‘a gift’, for ‘a portion of medicine’. In like a dose of salts [M19th], ‘very quickly and efficiently’, the salts referred to are Epsom salts or magnesium sulphate. They have had a variety of medicinal uses since the mid 18th century, most notably as a very effective and fast-acting laxative. The name Epsom salts comes from the town of Epsom in Surrey, where the crystals were first found.