Almost half of Australians have used the internet to self-diagnose medical conditions, according to a report released this week, while one in 10 between the ages of 18 and 34 have bought prescription drugs online.

Dr Thomson said though the online trend did raise some concerns, there were also advantages to easy access to health information and medications over the internet.

"When people visit their GP, their GP can examine them and have their past medical history on hand - so of course GPs know a whole lot of stuff that Dr Google doesn't," he said.

"However it's not always a bad thing if people type in their symptoms on the internet and do a bit of research - it may help them to rule things out or make some good decisions for their health.

"They often then still visit their GP armed with some background knowledge and are able to ask some really good questions."

The Milton GP said people had long sought a range of health opinions - from magazine articles to health brochures to alternative health practitioners.

"We counsel people to adopt a commonsense approach and would hope that any medical advice, be it online or otherwise, is given with the warning that if symptoms persist, see your doctor," he said.

"We would always be concerned if people delay treatment or not seek treatment because of the information they've received elsewhere."

The Consumer Health Management Trends report, commissioned by Good Price Pharmacy Warehouse, showed that some people bought prescription medication online because it was cheaper, or to avoid visiting a GP.

Dr Thomson said there were some reputable online pharmacies operating in Australia.

"Online or mail order pharmacies have been quite useful for people as they don't have a shopfront to run so medications like paracetamol can be significantly cheaper," he said.

"In cities and larger towns there's a lot of discount pharmacies but in smaller or country towns, there's not the same access to those."

Dr Thomson said complications arose when people ordered medications that reacted adversely with other medications.

"Viagra, for instance, can react with angina medication," he said.

He advised people against obtaining prescriptions or over-the-counter medications from overseas websites.

"You can place yourself at great risk.

"You may not get what you paid for or you might get a medication that includes ingredients that are banned in Australia."