The sister of former One Direction star Louis Tomlinson died after taking a “perfect storm” of drugs, a probe into her demise revealed this week.

Felicite Tomlinson, 18, was determined to have a fatal cocktail of cocaine, Xanax and OxyContin in her system when she died in March at her London apartment, the Telegraph reported.

“It was the perfect storm,” Coroner Shirley Radcliffe told a West London court.

The singer’s half-sister purchased cocaine with her friend Zainab Mohammed the night before she was found dead, according to Radcliffe.

Radcliffe questioned Mohammed in court about the teen’s final hours, which revealed the pair did coke with another pal.

“A male friend came over and you did lines [of cocaine], one or two, but you felt unwell,” Radcliffe said to Mohammed. “You saw [Felicite] do more lines but you didn’t know how many she did.”

Radcliffe said the teen was still breathing when Mohammed checked around 5 a.m. but she was unresponsive by noon.

The pop star’s sibling had been taking drugs on a regular basis to cope with her mother’s death in 2016 from leukemia, according to officials. Though they weren’t in her system, she had used MDMA, acid and cannabis in the past.

Her primary care physician, Paul Eulinger, said she “refused to give up drugs in the knowledge they could kill her.”

The investigation into her overdose concluded this week that her death was an accident, the Telegraph reported.

“She was an individual who took drugs deliberately and has succumbed to their said effects accidentally,” Radcliffe said. “There is no indication this was a deliberate attempt to end her life.”

Felicite was one of the former One Direction singer’s seven younger siblings, and he thanked fans for their support.

“Just wanted to thank everyone for their lovely words over the past couple of weeks,” he wrote on Twitter.