A ten-fold increase in hospital treatments for cannabis poisoning or dependence among people in their 30s and 30s suggests the habit has detrimental health consequences for hard-core long term users.

While overall cannabis consumption has decreased over the past decade, the rate of hospital treatment increased, according to Australian research.

The study shows that while treatment rates are highest among people in their 20s, the steepest increase has been among older people, with those in their 30s slightly less likely to seek help than younger people by 2007.

According to the findings of the National Drug and Alcohol Research at the University of NSW, people in their 30s were being treated at only half the rate of their younger counterparts, seven years earlier.

Their faster rise in cannabis-related health problems coincided with greater frequency of daily use.

These people started their use early and have (in some cases) then gone on to develop problems, Amanda Roxburgh, the study leader said.

They might not necessarily think they have a problem with their use until it kicks into crisis mode.

Nearly 50 per cent of people in the 20s were more likely to have used cannabis in a one-year period compared to those in their 30s. Of those who did so, nearly 20 per cent of the older age group had developed a daily habit, compared to 15 per cent of younger adults.

Jan Copeland, head of the National Cannabis Prevention and Information Centre, said older people were more likely to consider cannabis safe.

These people come from age groups where cannabis is a benign herb and natural, she said. But when you are doing something every day you don't realize the difficulties when you try to stop.

Medicine