Going shopping with her brother convinced one woman to launch a class action lawsuit on behalf of women across Quebec.

Aviva Maxwell said the trip to pick up deodorant revealed that she was paying more -- much more -- for the same items as her brother.

"I noticed that even if the label was the same, his were approximately twice as big as mine, and they were both on sale, both for the same sale price," said Maxwell.

"I was flabbergasted."

She looked into the issue and learned that many products marketed to women are more expensive their their male-oriented counterparts.

The so-called "pink tax" can be expensive, affecting everything from dry cleaning to haircuts and more.

Data-mining company Parsehub looked at more than 3,000 products sold in Canada, including razors, soap, and shampoo.

It found that, gram for gram, items sold to women cost an average of 43 percent more.

"It's straight up discrimination," said lawyer Michael Simkin.

Looking at Degree-brand deodorant, Simkin has filed for permission to launch a class action lawsuit against Unilever and eight retail chains.

"They are absolutely identical in terms of all the ingredients. The fragrance might be different but fundamentally it's the same product. So let them try and explain why that makes sense to charge women up to 50 percent more," said Simkin.

CTV News reached out to Unilever, the eight retail chains named in the legal filing, and the Retail Council of Canada. Not one organization wished to comment.

Marketing professor Jacques Nantel said there might be some slim justification for higher prices.

"Because you don't have the same volume of sale, the cost per product has to be pushed up for retailers to make the same profit," said Nantel.

However he did not think it was a particularly good argument.

"Is that something that should be condemned? Yeah, it should be. But again it's a retail type of accounting mentality," said Nantel.

Retail experts said it's always advisable to buy unisex products as a way of saving money, but Maxwell said that, too, can be discriminatory.

"They do have the obligation to right that wrong," said Maxwell.

The legal application for the class-action lawsuit is currently being studied by the courts. Maxwell and Simkin hope that they will get permission to proceed.