The ACCC is taking GlaxoSmithKline (GSK) and Novartis to the Federal Court over “false or misleading” pain medication marketing.

The regulator says patients are likely to have been “misled” by the more expensive pain relief cream Voltaren Osteo Gel, which is exactly the same as regular Voltaren.

ACCC chairman Rod Sims says the products contain the same amount of the ingredient that reduces pain and inflammation.

“We allege consumers are likely to have been misled into purchasing Osteo Gel, thinking it is different to Emulgel and more effective for treating arthritis, when this is not the case,” he said.

“In fact, the product has an identical formulations to Emulgel and both products are equally effective in treating not only osteoarthritis, but also a range of other pain conditions.”

Consumers pay 33 per cent more for Voltaren Osteo Gel than for standard Voltaren.

“We allege GSK and Novartis engaged in a deliberate commercial strategy to differentiate the products in a way that was likely to mislead consumers,” Mr Sims said.

“The alleged conduct is particularly concerning, given the significant penalties handed down by the court against the makers of Nurofen for what we consider to be similar conduct.”

GSK recently changed its Osteo Gel packaging to point out it has the “same effective formula as Voltaren Emulgel”, but the ACCC says this amended packaging could be misleading too.

The case is similar to the ACCC’s campaign against Nurofen Specific Pain products last year.