Young people who smoke cannabis regularly slide further down the social ladder than their parents, a study has revealed.
Those who use the Class B drug at least four times a week over several years end up in less skilled jobs than their family, researchers found - meaning they earn less money.
They could also see their ambition hampered by fellow cannabis smokers who do not aspire to material wealth, and face more social issues.
Scientists followed 947 young adults in New Zealand from the age of 18 to 38 - and were surprised at the extent to which cannabis is linked with reduced appetite to get ahead. The results showed that on many indicators of social mobility, by mid-life the effect of heavy marijuana use was worse than that of heavy drinking.
Lead researcher Magdalena Cerda, of the University of California, Davis, said: "We found that regular cannabis users experienced downward social mobility and more financial problems - such as troubles with debt - than those who did not report such persistent use.
"In fact, we found that cannabis dependence was worse than alcohol dependence in the case of financial difficulties and food insecurity. Regular use could also lead people to get involved with friends who discourage work-related achievement."
She added that she was "surprised at the robustness of our results".
The study - which was published in the journal Clinical Psychological Science - found that the economic and social consequences remained even after taking into account other factors such as lower intelligence, depression and coming from poorer backgrounds.
Researchers also discovered that people dependent on marijuana had more problems linked to anti-social behaviour, including relationship difficulties and domestic violence.
In Britain, about eight million people admit to smoking cannabis, with at least a third of youngsters claiming to have used it.
Previous studies have shown that frequent use can lead to a string of cognitive problems, particularly among the young whose brains are still developing.
Findings suggest that the drug can cause a user's vocabulary to shrink and trigger "schizophrenia-like symptoms".
Cannabis has been legalised for recreational use in four US states. However Professor Cerda added that marijuana "did not appear to be safe, and may be just as harmful as alcohol".
- Daily Mail