Jasmin Duddy was aged only 21, with her whole life ahead of her, when she was found unresponsive at a house in Galliagh in February.
Mum Pauline Duddy said a subsequent autopsy examination revealed Jasmin had Lyrica in her blood stream.
She sounded the warning after three drug-related deaths in the North West earlier this month.
Police Derry City and Strabane say officers are trying to track down a batch of extra-strength Lyrica tablets.
The drug is normally used to treat pain, epilepsy and anxiety.
Pauline has called for the courts to mete out tougher sentences on drug dealers and said more families will be left heartbroken unless more is done to tackle drug addiction.
Ms Duddy previously told the Derry Journal that her daughter had “the biggest heart and would have done anything for anyone”.
She told BBC News NI her daughter had been attempting to kick her addiction issues and was receiving treatment at Woodlea House at Gransha Hospital.
Ms Duddy said that on 1 February she received a call from her daughter, and knew by the sound of her voice that she was intoxicated.
“When the phone call ended, I texted her and said please sober up because I knew she had taken something. She then replied back saying: ‘Mum, I’m trying.’
‘We are the families left behind’
“So at 4 o’clock in the morning I was asleep and then there was police at the door and they said they wanted to come in to discuss a sensitive matter and they told me that my daughter was found deceased.
“I don’t understand why that day – that’s the question that keeps going round my mind – why that day did she decide to put those tablets in her mouth,” she added.
“She was off all the tablets, she was doing really well, and I don’t know what changed on the 1st February to make her put tablets into her mouth. That will never be answered.”
Ms Duddy said she only received the post-mortem examination results a few weeks ago which showed Jasmin had Lyrica in her system.
“It has left the whole family devastated and there’s a lot more families going through the exact same at the minute – we are the families left behind.”
Ms Duddy believes the drug problem in the north west is getting worse and said more needs to be done to tackle it.
“You can get drugs quicker than you can get chocolate out of the shop,” she told the BBC.
“It’s getting sold under your eyes, it’s getting passed under your eyes and it’s just horrific.
“It is all vulnerable, naive young people who are being preyed on.”
Ms Duddy has set up a petition called ‘Stop the street drugs’.
“I want the law changed for drug dealers to be prosecuted with murder. There are young people dyng everyday.”
You can sign the petition here: https://secure.avaaz.org/community_petitions/en/northern_ireland_assembly_stop_the_street_drugs/?fHVmCtb&utm_source=sharetools&utm_medium=facebook&utm_campaign=petition-1709138-stop_the_street_drugs&utm_term=fHVmCtb%2Ben&fbclid=IwAR0cr8KSEGHewiQEWxdLj8TgS3du2SQsOIMPir1eVL_AxQ-knnMPeWZQ1jw
Last week a Derry priest warned that the drug problem in the city has reached crisis point.
Fr Joe Gormley said the premature deaths of young people as a result of drug-taking is occurring more frequently than ever before.
Parish priest in Holy Family, Fr Gormley was speaking following the deaths of three young people in suspected drug-linked incidents.
Police believe three unexpected deaths in the city last weekend were linked to the prescription drug, Pregabalin, or as it as commonly know as Lyrica.
Derry Magistrates’ Court was told earlier this week that a further five cardiac arrests in the city might also be linked to Lyrica.
Two further people have been hospitalised since the weekend as a result of suspected Lyrica use.A man and woman were taken to hospital by ambulance from a city centre address.
Fr Gormley told UTV news he was concerned at the impact of increasing drug use in the city.
He said: “I believe it’s a problem which in my experience as a priest here in the city is growing.
“The premature deaths of young people in events like this (last weekend’s tragic deaths) is happening more frequently.”
Fr Gormley said he has buried too many young people in the city because of drug misuse.
He said the pain of each death was unique to the families involved.
He added that while people might want to “run away” from the problem it could only be dealt with if the whole of society worked together.Tags: