New Health Canada regulations requiring cosmetics manufacturers to list ingredients on product labels take effect on Thursday.

The regulations will be phased in over the next two years to allow companies time to use up current stock while making the necessary changes to their labels, Health Minister Tony Clement's Press Secretary Erik Waddell confirmed to CTV.ca.

In the meantime, manufacturers are required to provide lists of ingredients until the new labels are produced, he said.

Mandatory ingredient labelling will allow consumers to make more informed choices when purchasing products such as makeup, perfume, skin cream, shampoo, toothpaste, soap, shaving cream, and deodorant, Health Canada said.

The government agency says the regulations are also designed to help consumers avoid cosmetics containing ingredients to which they may be sensitive.

Under the new rules, the list of ingredients must be disclosed on all cosmetic product labels, using recognized names from the International Nomenclature of Cosmetic Ingredients (INCI) system.

Health Canada says INCI is used in the United States, European Union, Japan and is recognized as a text that is both multinational and multilingual.

The system was designed so that universally-recognized symbols represent a substance that may otherwise appear under many different trade names.

"By allowing only INCI names, the consumer needs to know only one "symbol" for a problematic ingredient instead of having to remember a number of different technical or trade names," a statement from Health Canada says.

Mandatory labelling will also allow for harmonization with trading partners, which use the INCI terminology on their products.

Health Canada estimates that Canadians spend about $5.3 billion on cosmetics each year.

According to the agency, there are more than 10,000 different ingredients that may be found in the cosmetics that Canadians use.

While most cosmetics do not pose a health risk, some ingredients can cause adverse effects ranging from mild irritations to severe allergic reactions in individuals with sensitivities.

Health Canada says that an estimated 2 to 5 per cent of adults may experience a mild reaction, such as a skin rash, to the chemicals in cosmetics.

However, a small percentage of individuals could see more serious reactions such as painful eye irritations, swelling, hair loss, and in rare cases, breathing problems.

Health Canada receives more than 50 adverse reactions reports a year but the agency believes that many more cases go unreported.