A ban on advertisements for prescription medicines is being called for by health experts.

The head of Otago University's Department of General Practice, Les Toop, says a ban on advertising medicines was long overdue.

"Advertising seeks to influence rather than to inform and leads to inappropriate use of medicines, which carry real harms and costs," Professor Les says.

The call for an advertising ban follows a Consumer New Zealand poll showing 57 per cent of those surveyed support banning adverts for medicines.

The poll found one in eight consumers requested a prescription medicine from a GP after seeing it advertised.

Professor Les says lifestyle drugs were often advertised, along with medicines for common conditions, such as asthma.

"People are being encouraged to take very powerful medicines more than they need."

Health professionals were also more likely to prescribe a drug if the patient specifically asked for it, he says.

Changes to the rules for advertising medicines could be considered in a review of the Therapeutic Products Bill that kicked off with consultation earlier this year.

"There's an almost universal call for a ban from all health professionals and consumer groups, so the ducks are all lined up... it's up to the politicians," Professor Les says.

Along with the US, New Zealand is one of the only developed countries in the world that still allows such adverts.

"It's a regulatory failure that we have not put in place such a ban 10 years ago," he says.

Advertising standards in New Zealand did not require the benefits and risks of medicines to be appropriately portrayed, he says.

"The pre-approval is done extraordinarily quickly and does not look at the balance of evidence, which is what you need to make an informed choice about medicines that are very powerful and you could be on for the rest of your life, which in many instances carry significant risk of harm."

-RNZ