"There are a significant proportion of heavy cannabis users who do experience withdrawal," he said.

"At least in the very small, uncontrolled trial, lithium may have the potential to alleviate the discomfort associated with that withdrawal and that's important because it actually might help people quit."

Lithium carbonate has been previously been shown to be help in the treatment of symptoms from cannabis withdrawal.

Dr Winstock says if a follow-up trial confirms the results, it will be one of the first studies to show medication can be used to help treat the symptoms of cannabis withdrawal.

"We hope this preliminary work will lead to a larger scale, multi-site, placebo-controlled study next year," he said.

"Given that cannabis is the most widely-used illicit drug in the world - and about one in 10 users become dependent on it - the possibility of finding an effective treatment to manage withdrawal is exciting."

Twenty regular cannabis users took part in the seven-day program, which involved taking a dose of lithium carbonate daily.

Of those participants, 29 per cent did not use marijuana at all in that time.