The competition watchdog is taking court action against the maker of the popular painkiller Nurofen, accusing it of misleading customers with some of its products.

The Australian Competition and Consumer Commission (ACCC) says at least four Nurofen products marketed as being formulated to treat specific ailments, including back pain and migraines, all contain the same active ingredient.

Tablets in each of the products contain 342 milligrams of ibuprofen lysine, with no other active ingredients listed.

The action has been instituted by the ACCC against Nurofen maker Reckitt Benckiser in the Federal Court.

The painkillers were approved by the Australian Register of Therapeutic Goods but the ACCC says the claims made about them are false and misleading.

"We allege that consumers have been misled into purchasing Nurofen specific pain products under the belief that each product is specifically designed for and effective in treating a particular type of pain when this is not the case," ACCC chairman Rod Sims said.

"The retail price of the Nurofen specific pain products is significantly above that of other comparable analgesic products that also act as general pain relievers.

"Recent price sampling conducted by the ACCC revealed that these products are being sold at retail prices around double that of Nurofen's standard ibuprofen products and standard products of its competitors.

"Our primary objective is to ensure these products are removed from sale because we think just being on sale is misleading and we allege can cause quite a lot of detriment to consumers."

Nurofen issued a statement in response to the allegations:

"Nurofen disputes any allegation of contravention of consumer law in relation to its pain-specific packaging. "All Nurofen packs are approved by the Therapeutic Goods Administration and comply with the TGA's regulatory guidelines. "Nurofen pain-specific products provide easier navigation of pain relief options in the grocery environment for consumers who are experiencing a particular type of pain."

Reckitt Benckiser also faces a fine of up to $1.1 million per breach if the Federal Court accepts the ACCC's allegations.

The recommended retail price for 24-tablet packets of the specific pain Nurofen products is $12.99 compared to $5.99 for an equivalent package of the conventional Nurofen.

Nurofen's website previously contained information indicating the different products should be used for specific purposes, but that advice has since been amended.

"Any of the four products shown on this page have the same ingredient and can be taken to provide effective temporary relief of pain and/or inflammation associated with either migraine, tension headache, back pain or period pain," the website now says.