Drug counsellor says it's easier to claim addiction than to get a job.
The number of people collecting benefits because of substance abuse has almost doubled since 2004.
One leading drug and alcohol counsellor believes the figure includes people who cannot find work, although Work and Income dismisses this.
Information obtained under the Official Information Act reveals 5714 people are on sickness and invalid's benefits because of alcohol- and drug-related health issues that prevent them working.
The latest figures are 2587 up on 2004 when the Ministry of Social Development reported 3127 people claimed sickness and invalid's benefits.
A sickness benefit is for people who can't work or are working less because they are sick, injured, disabled or pregnant. An invalid's benefit is for people limited in how much work they can do.
Auckland has the highest number of beneficiaries, with 1603 people claiming a sickness benefit and 366 claiming an invalid's benefit last year. Of those, 1014 were for alcohol abuse and 955 were for drugs.
Canterbury followed with 489 people on a sickness benefit and 357 on the invalid's benefit.
A slight decrease has been noted in the past two years since a Work Capacity Medical Certificate came into effect in September 2010. GPs send certificates to Work and Income when assessing whether someone is eligible for a benefit.
Alcohol and drug counsellor Roger Brooking blamed the 80 per cent increase on unemployment. He claimed doctors and case managers were sometimes ticking the "drug and alcohol box" without merit because it was easier than finding someone a job.
"If someone has a bit of a cannabis problem or drinking problems that are not that serious then sometimes it is easier for the doctor or the case manager at Work and Income to suggest that this person go on to the sickness benefit because there are no jobs available," Brooking said.
National Addiction Centre director professor Doug Sellman said doctors' attitudes towards alcohol and drug users had become more sympathetic.
"Doctors are much more likely these days to view addiction as no more 'self-inflicted' than traditional medical conditions such as cancer, diabetes or heart disease are, and therefore are more likely to treat people with addictions with similar compassion and understanding to these traditional medical conditions than they perhaps did 20 or 30 years ago," Sellman said.
Work and Income's deputy chief executive Debbie Power said comments that suggested Work and Income would rather put people on a sickness or invalid's benefit than try to find them a job were inflammatory and wrong.
"Our case managers continue to work hard every day to get people into work.
"Work and Income is in the business of helping people find work - we're not here to shuffle people around."