A 10-year-old boy has required what's believed to be the largest dose of antivenom administered in Australia to survive being bitten by a funnel-web, on the NSW Central Coast.

Matthew Mitchell was working in a shed with his father, Darren, at their Berkeley Vale property on Monday when he reached inside a shoe and was bitten on the finger by the deadly spider.

Mr Mitchell used Matthew's shirt to apply a tourniquet around his arm and drove the boy to the nearest open medical facility - a chemist.

Paramedics were called and treated Matthew before taking him to Gosford Hospital.

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He was given 12 vials of antivenom which is a record, according to Australian Reptile Park general manager Tim Faulkner.

"I've never heard of it, it's incredible," he told AAP on Friday.

"To walk out of hospital a day later with no effects is a testament to the antivenom."

An average funnel-web bite usually requires three to five vials of antivenom.

The male funnel-web is five times more venomous than the female, Mr Faulkner said, describing Matthew's bite as "significant".

"It would have been a fatal bite (without antivenom) there's little to no doubt of that," he said.

"A small child is more vulnerable - but that bite would have killed an adult."

Matthew's mother Shelly told AAP her son was "doing well" since leaving hospital.

She said she was keen to tell the family's story to warn others of the dangers posed by funnel-web spiders. Mr Faulkner praised the quick-thinking of Mr Mitchell.

"He was rattled but he should be very proud of himself, especially for applying a pressure immobilisation bandage," he said on Friday.

The offending spider was captured and taken to the reptile park where it is now part of the antivenom milking programme.

A month ago the Australian Reptile Park put a call out for live funnel-web spiders as its antivenom stocks were critically low.

"We're the sole supplier of funnel-web venom for the production of antivenom," Mr Faulkner said. February and March are peak mating season for funnel-webs.

Males are out looking for love but if it gets too hot they look for dark places to hide.