The maker of Nurofen has co-operated with the investigation and intends to plead guilty to the charges.

The Commerce Commission has laid 10 charges against Reckitt Benckiser (New Zealand) alleging it misled the public about the nature, characteristics and suitability of its Nurofen specific pain range products.

Eight charges under the Fair Trading Act relate to the promotion and packaging of Nurofen Migraine Pain, Nurofen Tension Headache, Nurofen Period Pain and Nurofen Back Pain.

Two other charges alleged that the advertising of the products on the company's website was likely to mislead or deceive consumers.

Reckitt Benckiser had co-operated with the investigation and intended to plead guilty to the charges, the commission said.

Do you feel you have been misled by Nurofen packaging? Send us an email to newstips@stuff.co.nz

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The Nurofen range marketed for back pain, period pain and migraines contained an identical active ingredient, and in December Reckitt Benckiser agreed to stop selling and marketing them. The packaging was changed in March.

"The commission alleges that both the website and the packaging of these products gave the overall impression that the products were targeted to provide relief for a specific kind of pain," the Commerce Commission said on Monday.

"The commission alleges this was misleading because the pain specific products contained the same ingredients and were equally effective in treating any of the types of pain specified."

The products under the commission's charges represented less than 5 per cent of the New Zealand Nurofen range, the manufacturer said.

"The Nurofen specific-pain range was launched in New Zealand to provide easy navigation of pain-relief within the grocery environment where pharmacy support is not available.

"The packaging of all Nurofen specific-pain products in New Zealand was changed by March this year to make clear that the different products could be used to treat other forms of pain."

The charges applied only to New Zealand and did not relate to other countries or other Nurofen products.

The company said it could not comment further as the case was before the court.