Drug-related deaths hit record levels in England and Wales last year, official figures have revealed.
Fatalities involving heroin and cocaine were both at their highest since comparable records started in 1993.
Statisticians pointed to increasing purity of substances as a possible factor behind the trend.
Overall, a record 3,674 drug poisoning deaths involving both legal and illegal substances were registered in 2015. Of these deaths 2,479, or two-thirds, involved illegal drugs only.
The Office for National Statistics (ONS) said the mortality rate from drug misuse was the highest ever recorded, at 43.8 deaths per million population.
ONS researcher Vanessa Fearn said: "Deaths involving heroin and morphine have more than doubled since 2012, partly driven by a rise in heroin purity and availability over the last three years.
"Age is also a factor in the record levels of drug deaths, as heroin users are getting older and they often have other conditions, such as lung disease and hepatitis, that make them particularly vulnerable."
The figures showed that there were 320 deaths involving cocaine, up from 247 in the previous year.
Mortality rates relating to the drug have increased for four years in a row, with the majority of cocaine-linked fatalities occurring in men aged 30 to 49.
The ONS report said the figure for cocaine-related deaths will include some where it was taken in the form of crack cocaine as it is not possible to separately identify crack from other forms of the drug at post-mortem.
It added: "Since cocaine is often taken alongside heroin, it is likely that changes in the purity and availability of heroin, as well as increases in the purity of cocaine, are contributing to the rise in deaths involving cocaine in recent years."
Ecstasy, or MDMA, was mentioned on 57 death certificates last year - the highest number in a decade. The ONS said the reasons behind the rise in recent years are unclear.
Deaths linked to new psychoactive substances - formerly known as "legal highs" - have increased sharply over the last five years, with 114 registered last year. New laws were introduced to clamp down on the substances earlier this year.
Deaths involving heroin and/or morphine doubled in three years to 1,201 in 2015
The figures also showed:
::Males were almost three times more likely to die from drug misuse than females
::People aged 30 to 39 had the highest mortality rate from drug misuse, followed by those aged 40 to 49
::The mortality rate from drug misuse was significantly lower in England than in Wales - 42.9 compared with 58.3 deaths per million population.
::Within England, the North East had the highest mortality rate from drug misuse in 2015 for the third year running (68.2 deaths per million population), while the East Midlands had the lowest (29.8 deaths per million).
Rosanna O'Connor, of Public Health England, said: "Drug use is the fourth most common cause of death for those aged 15-49 in England and we know that the majority of those dying from opiates have either never, or not recently, been in treatment.
"Reassuringly, overall drug use has declined and treatment services have helped many people to recover, but there is a need for an enhanced effort to ensure the most vulnerable can access treatment."
Izzi Seccombe, chair of the Local Government Association's community wellbeing board, said councils are committed to ensuring that drug users get the right support and spend more on drug and alcohol treatment than in any other area of public health.
She added: "However, with public health grants for local authorities being cut by 9% over the next four years... no service is immune from spending reductions, which could seriously undermine our efforts to prevent all kinds of major health conditions."