A new study shows homeless people die 20 years earlier than those living in a home.
The study found homeless people in Auckland die at an average age of 63.
Researcher Simon Thornley says drugs were revealed as a key factor in the shortened lifestyle.
"A lot of them have issues with addiction, whether that's alcohol, tobacco, cannabis - and I think addiction issues mean that you don't prioritise looking after yourself," he says.
Mr Thornley adds the findings also showed people who excessively smoke cannabis die earlier than those addicted to alcohol or tobacco.