In 1874, an English researcher, C.R. Wright, first synthesized heroin by boiling morphine and acetic anhydride. His early testing of heroin – then known as diacetylmorphine – showed undesirable side effects such as anxiety, sleepiness and vomiting immediately following administration. Accordingly, he discontinued his research. Over 20 years later in 1895, German scientist Heinrich Dreser and his colleagues at the pharmaceutical company Bayer continued Wright’s studies and declared diacetylmorphine successful in treating many common respiratory ailments.