This winter brought with it a particularly brutal flu season.

If you were one of the fortunate ones, you got some medication, stayed in bed for a couple of days and recovered.

But for those who live on the streets, it's an entirely different reality.

Medical clinics can be intimidating and expensive places, and medication costs are often beyond the reach of those living rough. Left untreated, sickness can quickly become acute.

Dr Coles says most of her patients are dealing with a range of complex issues. ( ABC RN: Fiona Pepper )

But in Melbourne, there's a glimmer of hope.

Every Wednesday for the past 18 months, Cohealth's Street Doctor program has provided free medical services to homeless patients.

GP Kate Coles and nurse Vaan Phongsavan have treated more than 200 homeless patients from their mobile surgery — a kitted-out minivan.

"Some of our homeless clients have problems with transport, have difficulties to get to an appointment on time, so by being there for them, we actually remove a lot of barriers," Dr Coles says.

A complex set of problems

Dr Coles describes the service as "a general practice — just in a bus".

"We do see the normal general practice things, people with colds and flus, but we do also see things that are more likely to happen to people who are homeless," Dr Coles says.

For example, she says bed bugs can be a real problem for people who are sleeping rough, couch-surfing or staying in temporary accommodation, and they can lead to serious skin infections.

She can also do mental health assessments on the bus, and refer people to see a psychologist, or to drug and alcohol treatment services.

Sorry, this audio has expired Hear more about the Street Doctor program

Working alongside Dr Coles, Ms Phongsavan is the first point of contact on the mobile surgery.

Their patients are often vulnerable people with complex problems, and Ms Phongsavan says having a non-judgemental approach to her work is essential.

"When we listen to our patients they actually become quite engaged," she says.

There is also a raft of complex reasons that lead to their patients being homeless.

"I think that it's true that people with mental illness are more vulnerable to homelessness ... but that's not everybody that we see on the bus," Dr Coles says.

Dr Coles says the lack of available affordable housing, unemployment and family violence are common factors leading to her clients becoming homeless.

One patient, David, has a 15-minute consultation with Dr Coles. After leaving the bus, he exclaims: "Kate's wonderful, it was very good. I got what I needed".

David speaks to the nurse and social worker. This is the first time he's accessed the service, and says he'd definitely use it again. ( ABC RN: Fiona Pepper )

Dr Coles says the bus also treats asylum seekers.

"We saw a fellow recently, he's an asylum seeker and he's been in the country for a number of years but has never had Medicare and has never been allowed to work, so he's got no money," Dr Coles says.

He had high blood pressure and high blood-sugar levels, and Dr Coles says she diagnosed him with diabetes.

Dr Coles says through the Royal Melbourne Hospital and a refugee health clinic, they were able to do blood tests and provide him with medication free of charge.

"But it's very difficult, people don't know that they can get access to these services and I think it's great if we are able to provide that linkage to the people," she says.

Often parked in central Melbourne alleyways or parks, the Cohealth Street Doctor treats patients in locations around the city. ( ABC RN: Fiona Pepper )

'Trying to do some good'

The Street Doctor program was initially funded jointly by Cohealth and Green Cross.

In addition to the Wednesday clinic, the City of Melbourne has recently committed to investing $200,000 to enable the service to operate on Mondays in the CBD.

Western Australia is the only other state with a similar service on offer, and Dr Coles says many homeless Australians go without adequate access to basic medical services.

She encourages other GPs and medical practitioners to get involved with similar programs.

"It's just wonderful to meet all these people and be part of the very big team that are trying to do something good," Dr Coles says.

But she does admit to feeling frustrated by what she sees while working as the street doctor.

"I do get sad, but I tend to get a bit more mad about the things that have caused people to become homeless," she says.

"Often people don't have much of a safety net and so then they find themselves on the street, and it's those sorts of things that really get me riled up."