A teenager had a fatal blood alcohol reading of 0.319 per cent after she played drinking games with her friends and family on her 18th birthday, an inquest in Perth has heard.

Nicole Emily Bicknell, who had just finished high school, consumed large amounts of melon-flavoured liqueur, pre-mixed vodka drinks and 95 per cent Polish spirit at a BBQ attended by 44 people on November 1, 2014.

The WA Coroner’s Court heard on Tuesday that she had 18 shots to mark each year of her life and continued to drink after that, but didn’t appear particularly drunk until the end of the night.

“She came up to me excited and said ‘I’ve made 18 drinks’,” her brother Steven Bicknell said.

No alcohol was provided at the gathering and guests, some of whom stayed the night, had to bring their own.

After their mother went to bed, Ms Bicknell, her brother and about nine others sat in a circle and played the “waterfall” drinking game, which involved her drinking straight from a bottle, continuously, while they took their turn to have shots.

The court heard she became incoherent after drinking the Polish spirit, which the guests turned to after other alcohol had run out.

“She spiralled quite quickly,” Mr Bicknell said.

“Her liveliness, bubbliness, talkativeness went downhill. She became quiet, more relaxed into her chair.”

His girlfriend Nyketta June Jenks, who didn’t drink during the party, told the court that before the drinking game, Ms Bicknell had taken a sip of the Polish spirit and exclaimed “that’s way too strong” before putting it down.

When it became clear she was drunk, Ms Bicknell’s boyfriend Jason Mark Roberts tried to give her water but it dribbled out of her mouth, so he and her brother put her to bed in the recovery position.

Mr Roberts monitored her for several hours, placing a bucket for her to vomit in beside her and checking her pulse and breathing, but eventually fell asleep himself.

When he woke, she had stopped breathing, felt cold and her lips had turned blue so he alerted the family and an ambulance was called.

Ms Bicknell was pronounced dead at hospital just after 7am.

Mr Roberts told the court she had drunk alcohol in the months before her birthday, but it was hard to tell how intoxicated she was. He said he believed she’d never encountered the 95 per cent spirit before that night.

“I would say she was a strong drinker,” he said.

“Outside, it didn’t fuss her. Inside, I couldn’t say.”

The three-day inquest is being held to draw public attention to the dangers of drinking games.