A mother-of-three who had battled with drug addiction for three decades died after taking an overdose of methadone.

Lisa Riding, 45, was found dead at her home in Ribbleton Drive, Accrington, on July 5, by her partner Alec Bleasdale.

An inquest at Blackburn Town Hall heard that Ms Riding was a known drug user, and was taking prescribed methadone as well as other drugs to treat depression, pain and anxiety.

Coroner Richard Taylor said toxicology reports had found there to be methadone present in Ms Riding's blood stream in the range encountered in fatalities.

He also said a number of other prescribed drugs were found, including Diazepam, Amitriptyline and Fluoxetine.

He said: "Mixing these drugs together may result in serotonin syndrome which can result in multiple organ failure.

"There was no heroin found in her system and a medical cause of death by drug toxicity was offered.

"The methadone was of a high dosage that could've caused death in itself, but the other drugs taken in therapeutic levels would've had an effect on the methadone, increasing the sedative affect."

The inquest heard that Ms Riding had been taking the heroin substitute for some time but had been on and off with it for weeks, which could have reduced her tolerance levels.

A statement from the drugs team at Inspire, who provided Ms Riding with support for amphetamine and opiate addiction, said she was offered one-to-one appointments, and it was known that she sometimes used heroin on top of her methadone treatment.

It was heard that in the days before her death, Ms Riding had missed some of her methadone doses and she was offered a course of treatment to mitigate the affects of a reduced tolerance in order to prevent an overdose.

Ms Riding's GP, Dr Kathleen Hewitt said: "She had a long history of drug abuse dating back to 1986, and also had a history of depression for which she was prescribed Fluoxetine, and was doing well on this from a mental health perspective.

"However, we had tried to get her off Diazepam but this was difficult as she kept coming back to ask for it."

Ms Riding's partner, Mr Bleasdale, said he believed her tolerance to the methadone had been lowered and she wouldn't have seen taking her normal dosage after a break as an overdose.

In concluding, Mr Newman said: "All the drugs in her system were prescribed, and I therefore return a conclusion of misadventure and say that Ms Riding died having ingested an excess of prescribed medication."