More than 200 hospital beds are occupied every day in Northern Ireland because of drink and drug abuse, a report has revealed.
Alcohol misuse alone is costing up to £900m annually, heaping pressure on an already stretched health service.
In 2019, the bill for A&E attendances linked to excess drinking was estimated at over £30m.
The number of people seeking help for drug abuse has also doubled since 2007, with deaths more than trebling.
Yet auditors found the Department of Health allocates a relatively small budget to tackling the problem.
The stark findings are set out in a report published today by the Northern Ireland Audit Office.
Its investigation of the region's addiction services highlights the cost of substance misuse to the public purse and calls for a review of health officials' strategy.
Comptroller and Auditor General Kieran Donnelly said: "This is an increasingly unsustainable burden.
"Alcohol and drug addiction are complex problems and don't occur in isolation. People need support with a wide range of issues, not just their addiction.
"While this report focuses on the services delivered by healthcare providers, it is clear only a joined up approach across the whole of government will begin to tackle this issue effectively."
The reports details how the health sector incurs significant costs dealing with alcohol and drug misuse. Around 25% of A&E consultants' time is spent dealing with alcohol-related incidents, reaching 75% at peak times.
Auditors estimated the cost of A&E attendances linked to drink abuse in 2018/19 at almost £33m.
Over 73,000 hospital bed days were occupied where substance misuse was recorded as a contributing factor in 2017/18. The majority of this relates to alcohol and equates to 200 hospital beds occupied every day.
Hospital bed days due to mental and behavioural issues caused by substance misuse have risen by 35% since 2013/14. In England, by contrast, they have fallen by 25%.
In 2009, the Department of Health estimated that alcohol misuse here costs around £680m annually.
Today's report puts the cost at £900m - a 75% rise. Of this figure, £250m falls directly on the Health and Social Care sector.
Alcohol-related crime makes up a substantial proportion of violent offences. It was a contributing factor in over 14,000 offences in Northern Ireland in 2018/19 - around 40% of all violent crime.
The report also found:
l Northern Ireland has the second highest rate of alcohol-related deaths in the UK - 17.4 per 100,000 in 2017. In England the figure was 11.1, in Wales it was 13.5 and in Scotland it was 20.5.
l While drink abuse remains the most prevalent substance issue here, the number seeking treatment for drug misuse has grown significantly, doubling from 2,107 people in 2007 to 4,183 people in 2019. The number of deaths relating to substance misuse trebled in the last decade.
l The majority of drug-related deaths now involve prescription drugs such as pregabalin and diazepam. Northern Ireland prescribes more pregabalin and diazepam per capita than anywhere else in the UK.
l The level of harm is most acute in areas of high deprivation, where deaths related to drug and alcohol misuse are around four and a half times that seen in the least deprived areas.
l Addiction services are also facing pressures. The Belfast Trust saw a 300% increase in referrals to its Substitute Prescribing Service between 2018 and 2019.
However, auditors noted the Department of Health allocates relatively little funding to tackling the issues.
Around £8m was allocated to implementing its drugs and alcohol strategy and a further £8m for statutory addiction services from the mental health budget - around 5% of the budget.
Today's report describes the department's performance monitoring of substance misuse services as very limited.
"Data collected is not reliable or complete, therefore the department cannot demonstrate services are effective or deliver value for money for the taxpayer," it states. "The department's substance misuse database has not been published for over two years due to quality issues."
Mr Donnelly added: "While the information that is available paints a worrying picture of a growing problem, it is disappointing that the department has little reliable information on outcomes for people seeking treatment for addictions."
His report recommends that clearly defined objectives and outcomes are built into the Department of Health's new alcohol and drugs strategy.
In response, Health Minister Robin Swann said: "Obviously the department will need time to consider the report in detail. However, I note many of the issues raised were already identified in the review of our current substance misuse strategy that was published by my department last year. Indeed action is already under way to address many of the issues outlined.
"For example, while the department and the health and social care system collects a range of data on treatment services, we have been working for the last year to improve the collation and the consistency of this data, and to improve the collection of outcomes measured at a regional level.
"This is a complex area as those engaged in treatment services will have different goals for their treatment.
"Work is under way to develop a new substance use strategy for Northern Ireland."