An inquest was held at Walton-on-Naze yesterday on Edward Clifford James, invalided from South Africa, where he served in the Suffolk Imperial Yeomanry. The deceased had lately been assisting his father, who is a cab proprietor, but had not paid for the cash received. The father asked for the money yesterday, and the son, replying that he would get it, went to his bedroom, returned, and, putting his hand to his side, remarked, "I am very sorry, I have got no money, and have taken poison." Death resulted from cocaine poison. - A verdict of "Suicide while of unsound mind" was returned. Evening Express, Saturday 16th August 1902
Cocaine was used as an anaesthetic back then, and you could buy medicines over the counter which contained cocaine, and also cocaine-laced cigars! But there must have been some awareness of it being dangerous for this man to have intentionally taken an overdose.
If I have it right, it wasn't until after the Defence Of the Realm Act (DORA) was passed in 1914, that the availability of cocaine in the UK was cracked down on, in May 1916. There's a Canadian soldier, buried at Shorncliffe, who died from a heroin overdose in 1915.