Jayden-Lee Green died a month before his second birthday, after his drug-addicted father gave him the heroin substitute methadone.
A serious case review has found his death could have been prevented if he was taken into care, away from his parents. The review said the professionals involved in his care missed opportunities to understand what was going on with Jayden-Lee's care at home.
Jayden-Lee lived with parents Jamie Green and Sonia Britton in Bristol. They were crack cocaine and heroin addicts and the toddler was found dead in his parents' bed after over-dosing on the heroin substitute last August.
The serious case review into Jayden-Lee's death found there was a lack of co-operation from his parents with everyone involved in dealing with them, which included drug agencies, midwifery and housing services, social workers and health visitors.
The report, which referred to Jayden-Lee as 'Child K' said: "What was lacking was the authoritative challenge to this lack of co-operation, there was a lack of enforcement of consequences. There was a lack of challenge by practitioners across the range of agencies.
The only way that Child K's death would definitely have been prevented was if he had been placed away from his parents.
The opportunity to do this was lost due to the failure to follow through on the initiation of care proceedings. However, a better-planned and authoritative approach to the family may also have prevented his death."
Jayden-Lee's dad was convicted of manslaughter and causing cruelty to a child and was sentenced to nine years in prison. His mother was convicted of child cruelty and causing or allowing the death of a child, and was jailed for four years.
The Bristol Safeguarding Children Board accepted the recommendations.
Professor Ray Jones, chairman of the Board, said: "They had a history of drug misuse and also, unfortunately, a history of being devious and manipulative in terms of their engagement with agencies.
"We want to drive home the message that giving methadone to children is dangerous, with potentially disastrous consequences, as in this case, which resulted in Jayden-Lee Green's death and his parents both serving prison sentences.
"The board accepts all of the recommendations in the report and we are giving particular attention to how we ensure all workers and agencies in contact with drug-misusing parents keep the safety and welfare of children as a major focus, and seek to challenge parents about the potential implications of their drug misuse on their parenting."
The Coventry Telegraph reports that during a press conference, some of the agencies involved with Jayden-Lee expressed regret at his death, adding that lessons had been learnt.