Sherlock brought the famous detective to the modern world, so many changes had to be made to the character, of which some messed with the canon. Among those is Sherlock Holmes’ drug use, with the series turning him into an addict. Created by Sir Arthur Conan Doyle, Sherlock Holmes made his debut in 1887 in A Study in Scarlet and became so popular, he appeared in a total of four novels and 56 short stories. The Great Detective has been adapted to all types of media for over a hundred years, and recent adaptations have reignited interest in Conan Doyle’s stories.
Among the most recent versions is the BBC’s TV show Sherlock, created by Mark Gatiss and Steven Moffat. Sherlock is set in modern-day London, meaning that the detective (played by Benedict Cumberbatch), his friend John Watson (Martin Freeman), and other characters from Conan Doyle’s stories had to be adapted to the present day. As a result, Sherlock Holmes used technology to his advantage but without relying entirely on it to solve his cases, but there were also other changes to the character that weren’t well-received by the audience, especially those familiar with the source material, as they ended up changing the Sherlock Holmes canon, and one of those was Sherlock’s drug addiction.
In Sherlock, the detective had struggled with drug addiction prior to the events of season 1, and this problem was casually mentioned a couple of times throughout the series. Later on, in the episode “His Last Vow”, Sherlock was found in an opium den by John and was believed to have relapsed, but it was all part of his investigation to take Charles Augustus Magnussen down, and then in “The Lying Detective”, Sherlock relapsed. While in the books it’s mentioned that the detective turned to drugs from time to time, mostly when he had no new cases and got bored, he didn’t have a drug addiction, and instead many fans argue that his real addiction was connected to his work, as he always felt the need to be working on a case, no matter how big or small. Moffat and Gatiss admitted that there are “more references to Sherlock Holmes laughing than there are to taking cocaine or morphine” and pointed out that it was important to “not get it out of context with the rest of the character”, but they completely failed at that.
An exact reason why Moffat and Gatiss decided to make Sherlock Holmes a drug-addict hasn't been revealed, but it was most likely just to add more drama to the arcs of Sherlock and John. Not so coincidentally, Sherlock’s drug problem became evident after the series brought him back from the dead and Mary Watson (Amanda Abbington) was introduced, which is when the quality of the series began to go down. Sherlock’s drug use ended up feeling like a desperate move from the writers to keep the interest and attention of the audience, but as many critics have pointed out, Sherlock didn’t even do a good portrayal of the detective’s addiction and simply used it as a plot device and a way of manipulating John. Of course, this is far from what the Sherlock Holmes canon established, with the detective only turning to drugs occasionally and just for recreational purposes when he got bored, as he needed his mind to be in constant stimulation.
Turning Sherlock Holmes into a drug-addict – and one who supposedly had it in such control that he could go down the rabbit hole for weeks and then leave it without much trouble, though he clearly had emotional triggers that sent him back to these substances – wasn’t Sherlock’s best decision, and was one that ultimately hurt the canon and the character itself, and was only used as a failed and unbelievable plot device.