Félicité Tomlinson, sister of the former One Direction star Louis Tomlinson, accidentally overdosed on cocaine, an anxiety drug and painkillers, an inquest has found.

The 18-year-old was found collapsed at her flat in Earl’s Court, west London, in March.

On Wednesday, at an inquest into her death, the coroner, Shirley Radcliffe, said a cocktail of drugs taken by the teenager had created “a perfect storm” but there was no evidence it had been “a deliberate act to end her life”. She recorded a finding of death by misadventure.

The inquest heard the teenager had turned to drugs after the death of her mother, Johannah Deakin, who died from leukaemia in 2016. Tomlinson was found collapsed on her bed by her schoolfriend Zainab Mohammed after the pair had taken cocaine the night before.

The coroner said of Mohammed: “You … say that both you and Fizz did lines of cocaine on the night of 12 March. You went to bed and saw Félicité do more lines, but you don’t know how many she did and then you fell asleep. You also said you had gone with her to buy cocaine on the night.”

Mohammed confirmed she was not aware of any other drugs being taken on that night.

A postmortem did not reveal any natural cause of death. The toxicologist Dr Susan Paterson said “toxic” levels of anti-anxiety and pain medications as well as cocaine were found in her blood.

The inquest heard Tomlinson’s dependency on drugs had grown in recent years. She visited her GP in August 2018 and “gave a history of recreational drug use over a year and on a consistent basis since the death of her mother”. She had taken overdoses and been admitted to drug rehabilitation.

A tribute by her father, Mark Tomlinson, was read out at Westminster coroner’s court. He said she was a “much-loved daughter and sister” and had from an early age “established herself as mischievous and wonderful with children”.

He added: “Félicité had huge hopes and aspirations for her future, a lot of which were beginning to come to fruition at her untimely passing. She is missed by all who knew and loved her.”

In the UK and Ireland, Samaritans can be contacted on 116 123 or email jo@samaritans.org or jo@samaritans.ie. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at www.befrienders.org.