Sales of supplements and complementary medicine are on the rise but many buyers may not be using them properly, which can place their health at risk.

A new study is under way to help pharmacists figure out how they can better provide advice to consumers taking such products.

Blackmores Institute, the research and education arm of supplement maker Blackmores, will conduct a survey in pharmacies from May to find out consumers' perceptions and usage of complementary medicine, including supplements and herbal products.

Dr Lesley Braun, director of Blackmores Institute, said public use of complementary medicine is increasing.

"This research is important to gauge the public's understanding of and literacy on complementary medicine, so that we can better equip pharmacists to take on a bigger primary care role and provide the best possible advice," she added.

The six-month study will involve face-to-face interviews with more than 300 consumers at pharmacy outlets islandwide.

According to the Health Supplements Industry Association of Singapore, whose members account for more than 90 per cent of the health supplement products marketed here, the demand has been increasing year-on-year by about 8 per cent.

Singaporeans spent about $594 million on supplements in 2015, according to the latest figures.

Currently, health supplements can be imported and sold without a licence from the Health Sciences Authority. But the authority has a post-market surveillance framework to detect adverse events associated with health products, said its spokesman.

Guardian pharmacist Grace Chew said many people who take complementary medicine have minimal knowledge of how the usage can affect them. This could be risky, especially if they are taking other medications.

Interactions between the two could cause unwanted side effects, such as unexplained muscle pain.

Pharmacists, especially those who work in retail outlets, are well placed to dispense the right information to the public.

"We can advise consumers on complementary medicine use and how it can interact with other medical conditions and medications," said Ms Chew.

Correction note: In an earlier version of the article, we referred to Dr Lesley Braun as a man. We are sorry for the error.