The death from necrotising fasciitis comes almost exactly a year after 18 people from the Glasgow area died after using contaminated drugs during part of a wider outbreak.
Health officials said the victim, who has not been named, was found to have died of necrotising fasciitis following a post-mortem in Glasgow.
The examination was ordered by the procurator fiscal after two other cases of the disease were found during the last week among drug users in the Greater Glasgow and Argyll and Clyde health board areas.
It is thought all three addicts became ill after injecting heroin. The two in hospital are said to be in a serious condition.
The death from necrotising fasciitis comes almost exactly a year after 18 people from the Glasgow area died after using contaminated drugs during part of a wider outbreak.
Dr Jim McMenamin, a public health consultant with Greater Glasgow Health Board, said: "This unfortunate death occurred before we had any indication that an outbreak was identified.
"The clinical condition of the two in-patients remains serious.
"Drug users can develop necrotising fasciitis following injection of contaminated material below the surface of their skin.
"I would wish to stress that there is little risk to the general public from the condition."
'Seek medical attention'
Health officials said the cases of the flesh-eating bug had come to light in the last week during routine checks of drug addicts.
Injecting drug users are more vulnerable to the illness, because it commonly enters the body through broken skin.
Dr McMenamin added: "Our advice remains the same, drug users should not inject and if their addiction is such that they must take heroin, it should be smoked and not injected.
"If there is any pain or swelling around an injection site they should seek urgent medical attention."
More than 30 heroin users in the UK and Ireland died last year after being infected by clostridium, with the largest number of cases concentrated in Glasgow.
About 1,000 cases of necrotising fasciitis are diagnosed in the UK each year, with about 60 to 80 proving fatal.
The disease commonly begins in an established wound or broken skin before penetrating the tissues beneath the skin, causing blisters to form.
Flu-like symptoms and diarrhoea can also occur, with patients developing toxic shock syndrome as the disease spreads to the underlying tissues.
If caught early it can be treated with antibiotics, but more drastic surgery can involve the removal of skin and even limbs to halt the spread of the bacteria.