On average, about 10 new cases are diagnosed in the Greater Glasgow and Clyde area each year as a result of drug injecting.
But the health board said that rose to 47 last year.
They are now warning drug users of the dangers of sharing needles and advising anyone who injects to get tested.
For the first time in almost 30 years, new diagnoses of HIV related to drug injecting was at a comparable level among gay and heterosexual men.
Investigations into the outbreak highlighted that some drug users were sharing needles, syringes, spoons and water when preparing and injecting their drugs.
It has also highlighted that there is low awareness of the risks of HIV from doing so.
Dr Catriona Milosevic, consultant in public health medicine at NHS Greater Glasgow and Clyde (NHSGGC), said it was "vitally important" that people who inject drugs do not share or reuse equipment.
She said: "This includes when injecting with close friends or partners - you can't guess whether someone has HIV, and they may have no symptoms and be unaware themselves.
"Everyone involved needs to use a new set of sterile injecting equipment every single time, including needles, syringes, water, filters, and spoons, to protect themselves and others. These are all available from injecting equipment services."
Dr Milosevic said the goal was to get people drug free, but until that is achieved the focus had to be on harm reduction.
Although there is no cure for HIV, there are now treatments which reduce the virus to what doctors describe as "undetectable" levels.
Dr Milosevic added: "Recent discussions have highlighted that those at risk are not aware of the huge advancements made in HIV treatment - there is still a perception that a diagnosis of HIV is a 'death sentence'.
"If people are diagnosed and start treatment early, which requires a test, they can have a similar life expectancy as the rest of the population."
Health officials in the Glasgow area have warned people who inject drugs about an outbreak of HIV after a near five-fold increase in the city.