Reckitt Benckiser has been asked to pay a penalty of A$6m (£3.56m; $4.42m) by the Federal Court of Australia, according to the Australian Competition and Consumer Commission (ACCC), the country's competition regulator and national consumer law champion.
The ACCC said the fine was for violating the Australian Consumer Law (ACL). It said the British consumer goods multinational had made misleading representations about its Nurofen Specific Pain products.
While representations on Reckitt Benckiser's website and Nurofen's product packaging showed that the products were each formulated to specifically treat a particular type of pain, the ACCC said this was not found to be the case.
"In fact, each Nurofen Specific Pain product contains the same active ingredient, ibuprofen lysine 342mg, which treats a wide variety of pain conditions and is no more effective at treating the type of pain described on its packaging than any of the other Nurofen Specific Pain products," an ACCC statement said.
The penalty follows the company admitting to the misrepresentation in December 2015. Trial judge Justice Edelman had in April 2016 ordered Reckitt Benckiser to pay a penalty of A$1.7m.
However, the ACCC went on appeal in May 2016 and the latest fine is a result of the Federal Court upholding the appeal. The court said it had found the earlier penalty "inadequate given the need for deterrence and the substantial consumer loss suffered".
Rod Sims, the ACCC chairman, said: "This is the highest corporate penalty awarded for misleading conduct under the Australian Consumer Law.
"The ACCC welcomes this decision, having originally submitted that a penalty of $6m or higher was appropriate given the longstanding and widespread nature of the conduct, and the substantial sales and profit that was made."
Justices Jagot, Yates and Bromwich who gave the joint decision, said: "The objective of any penalty in this case must be to ensure that Reckitt Benckiser and other 'would-be wrongdoers' think twice and decide not to act against the strong public interest."