A major report on the health-effects of marijuana and cannabis-derived products has found evidence of both therapeutic and harmful effects.

Medicinal cannabis effectively treats chronic pain and significantly helps those with multiple sclerosis (MS), a major US report on the health effects of marijuana has found.

But recreational cannabis smoking is likely to increase the risk of schizophrenia and may even trigger a heart attack.

The US National Academies of Science, Engineering, and Medicine has released a 400-page report offering a rigorous review of more than 10,000 scientific research papers published since 1999 about what is known about the health impacts of marijuana and active chemical compounds known as cannabinoids - ranging from pain relief to risks for causing cancer.

As attitudes towards the illicit drug soften in response to use of medicinal cannabis, it's important that Australians are well educated on the harmful effects of its recreational use, says Alcohol and Drug Foundation National Policy Manager Geoff Munro.

A paper published last year in The Lancet Psychiatry journal showed an increasing number of US adults using marijuana as fewer people perceived the drug as harmful.

The National Drug Strategy Household Survey found approval of marijuana use for recreational purposes in Australia rose from 8.1 per cent in 2010 to 9.8 per cent in 2013.

"There is no doubt that marijuana is harmful," Mr Munro told AAP.

"We need a more literate community about the potential benefits and harms of any drug use and cannabis is just the same. The fact that it can be used for medical purposes to relieve pain or other debilitating conditions doesn't mean that it is safe or without harm and I think that is the debate we need to have," Mr Munro said.

WHAT THE CANNABIS REPORT FOUND

• Therapeutic Effects: Patients treated with medicinal cannabis more likely to experience significant pain reduction. Substantial evidence that oral cannabinoids effectively reduced muscle spasms related to MS and nausea and vomiting associated with chemotherapy.

• Cancer: No evidence linking smoking cannabis to increased cancer risk associated with tobacco use.

• Heart Attack: Some evidence suggesting cannabis smoking may trigger a heart attack. More research needed to determine risk of heart attack, stroke and diabetes.

• Respiratory Disease: Regular smoking of cannabis associated with more frequent chronic bronchitis episodes, chronic cough and phlegm production. Unclear if cannabis use linked to chronic obstructive pulmonary disease or asthma.

• Mental Health: Likely to increase risk of developing schizophrenia, other psychoses and social anxiety disorders. Also increases risk of developing depression. Heavy users more likely to report suicidal thoughts than non-users.

• Psycosocial: Learning, memory and attention impaired after immediate cannabis use but limited evidence suggesting such impairments continue after the cessation of smoking cannabis.