"People become quite anxious, the most commonly reported symptom is irritability, people can have disturbed sleep, some people report constipation, you just become very, very uncomfortable," he said.

"It's usually days one to three you'll have quite severe withdrawal symptoms, then you'll have a little lull and then it's about days six and seven, with no other nicotine to actually assist, you'll have another burst of cravings."

Mr Lunney's job is to help patients at Bendigo Health avoid some of the worst of those symptoms through the hospital's Supporting Patients To Be Smoke Free program, which aims to assist people to stop smoking comfortably.

"The chemical addiction is what keeps people smoking," he said.

"You have receptors in your brain that take nicotine, they don’t take anything else, it’s a lock and key hypothesis, and when you smoke you actually feed those receptors and the more you smoke the more receptors you have.

"Over the years you will develop a habit of smoking, which they call 'the hand to mouth fixation', where people are used to moving their hand up and down to their mouth to have a cigarette, so if we can address the chemical side of it, the actual nicotine addiction, we can then discuss with people ways to deal with the habit of having something in your hand, or even the cues to smoke such as meeting friends and having a cigarette."

The program, launched in the lead up to yesterday's World No Tobacco Day, aims to support patients who smoke to manage their nicotine addiction when they enter the hospital's smoke free grounds.

Project leader Pauline Nolan said entering hospital was a stressful time for many people and not being able to smoke could add to that stress.

"We're not there to tell people they have to stop (smoking) we just realise that they're here in an environment where they can't smoke," she said.

"We are looking at assessing everyone's nicotine dependence, which shows whether they're addicted to nicotine, and if they are we're going to provide them with free nicotine replacement therapy and they can get a referral to the tobacco treatment specialist nurse as well, or support once they leave the hospital."

The program operates in conjunction with Bendigo Community Health Services and also offers support to staff who wish to quit.