Britain's advertising watchdog is investigating claims made by the makers of Nurofen after an Australian court ordered the company to stop selling several versions of the popular painkiller.
Australia's Federal Court ruled that Reckitt Benckiser, the British firm which produces the over-the-counter drug, deceived consumers by selling Nurofen painkillers that were identical to its standard ibuprofen pills, but nearly twice as expensive.
The UK's Advertising Standards Authority has now confirmed it is investigating 12 complaints about a television advert for Nurofen Express.
The watchdog is examining whether the advert was misleading because it implies that the product directly targets muscles in the head.
It is also looking into whether viewers were misled by the claim that the Nurofen Express "gives you faster headache relief than standard paracetamol or ibuprofen".
An ASA spokesman said: "We received the complaints in February and launched an investigation in March. This is a complex case and our investigation is ongoing.
"The advertiser is providing evidence to substantiate its claims, we're carefully assessing that and we'll publish our findings in due course."
Australia's consumer watchdog launched court action in March, arguing that consumers were being tricked into thinking that four products - Nurofen Back Pain, Nurofen Period Pain, Nurofen Migraine Pain and Nurofen Tension Headache - were designed to treat a specific type of pain, when in fact, they were all the same.
"None of the four products is any more or less effective than the others in treating any of the particular symptoms," Justice James Edelman wrote in his judgment.
A spokeswoman for Nurofen said the Australian court ruling did not affect its UK products and they would continue to be available.
A Nurofen spokeswoman refused to comment on the ASA investigation as it was "ongoing".
The UK's Medicines and Healthcare Regulatory Products Agency has no remit on medicine pricing and tends to intervene only when a product's name or description makes a medically misleading claim.
