Sam Woodhouse, 18, has spent at least two nights exposed to the elements on a 135,000 acre property at risk of dehydration, snake bites and injury.

The teenager had been staying at the remote Upshot Station, 130 kilometres southwest of Longreach, for about 10 days before he went missing and had been planning to jackaroo at the station for about six weeks.

The search on Thursday was called off about 5pm as the sun set and will start again at first light on Friday but the teenager could survive in the outback for anywhere between a few hours and a few weeks, according to survival instructor Nick Vroomans

"If he's moving during the day and working really hard, he could be gone in 24 hours," he said.

"...if he's stopped and looked after himself then he can last a few days and if he's found water, it could be two weeks."

Mr Vroomans said the best thing the teenager could do is sit still and wait for help to come to him, moving only early in the morning or late in the evening to find water.

"Food is of no importance whatsoever," he said.

"You can go 30 days without food, it's a common misconception [that it is imperative].

"People get all wound up about food but water is very, very important.

"If he doesn't find water he can be gone in two or three days."

Mr Woodhouse was reported missing at 10.30am on Wednesday after one of the station owners went to get him out of bed, believing he had slept in.

Instead she found the bed empty and Mr Woodhouse's running shoes, along with a backpack, missing with him.

It was not uncommon for Mr Woodhouse to go running and the fact he had left his wallet behind also led police to conclude he may have gone out exercising and become disoriented.

Mr Woodhouse was last seen at 5.30pm on Tuesday so police are unsure if he set off from the homestead for a run on Tuesday evening or Wednesday morning.

Neighbours from next door properties which are actually hundreds of kilometres from Upshot station have joined the search since Wednesday using their own small planes, helicopters and horses.

Mr Woodhouse's family are waiting anxiously in his native England for news of his whereabouts, being kept up to date by officers who have set up their search base at the homestead at Upshot Station.

His sister, Rebecca Woodhouse, first showed her worry when she urged anyone on Facebook who has heard from him to contact her straight away but the posts have gradually become more urgent.

"Would be a great birthday present if my brother would just turn up and ask what all the fuss is about!" She posted on Thursday morning, Australian time.

Thursday's search for Mr Woodhouse ended as the sun went down about 5pm but police are planning to start again at first light.

"[What he can eat in the bush] depends on how handy he is," Senior Constable Shane Ranger said.

"...Dehydration, snake bite, injury, those are the factors we are concerned about."