Because underarm antiperspirants or deodorants are applied near the breast and contain potentially harmful ingredients, several scientists and others have suggested a possible connection between their use and breast cancer. However, no scientific evidence links the use of these products to the development of breast cancer.

Aluminum-based compounds are used as the active ingredient in antiperspirants. These compounds form a temporary “plug” within the sweat duct that stops the flow of sweat to the skin's surface. Some research suggests that aluminum-containing underarm antiperspirants, which are applied frequently and left on the skin near the breast, may be absorbed by the skin and have estrogen-like (hormonal) effects.

Because estrogen can promote the growth of breast cancer cells, some scientists have suggested that the aluminum-based compounds in antiperspirants may contribute to the development of breast cancer. In addition, it has been suggested that aluminum may have direct activity in breast tissue. However, no studies to date have confirmed any substantial adverse effects of aluminum that could contribute to increased breast cancer risks. A 2014 review concluded there was no clear evidence showing that the use of aluminum-containing underarm antiperspirants or cosmetics increases the risk of breast cancer.

Some research has focused on parabens, which are preservatives used in some deodorants and antiperspirants that have been shown to mimic the activity of estrogen in the body’s cells. It has been reported that parabens are found in breast tumors, but there is no evidence that they cause breast cancer. Although parabens are used in many cosmetic, food, and pharmaceutical products, most deodorants and antiperspirants in the United States do not currently contain parabens. The National Library of Medicine’s Household Products Database has information about the ingredients used in most major brands of deodorants and antiperspirants.

Only a few studies have investigated a possible relationship between breast cancer and underarm antiperspirants/deodorants. One study, published in 2002, did not show any increase in risk for breast cancer among women who reported using an underarm antiperspirant or deodorant. The results also showed no increase in breast cancer risk among women who reported using a blade (nonelectric) razor and an underarm antiperspirant or deodorant, or among women who reported using an underarm antiperspirant or deodorant within 1 hour of shaving with a blade razor. These conclusions were based on interviews with 813 women with breast cancer and 793 women with no history of breast cancer.

A subsequent study, published in 2006, also found no association between antiperspirant use and breast cancer risk, although it included only 54 women with breast cancer and 50 women without breast cancer.

A 2003 retrospective cohort study examining the frequency of underarm shaving and antiperspirant/deodorant use among 437 breast cancer survivors reported younger age at breast cancer diagnosis for women who used antiperspirants/deodorants frequently or who started using them together with shaving at an earlier age. Because of the retrospective nature of the study, the results are not conclusive.

Because studies of antiperspirants and deodorants and breast cancer have provided conflicting results, additional research would be needed to determine whether a relationship exists.

No. The best studies so far have found no evidence linking the chemicals typically found in antiperspirants and deodorants with changes in breast tissue.