There is currently no strong scientific evidence that shows antiperspirants cause breast cancer.

Since antiperspirants tend to include aluminum and are applied near the breast tissue and lymph nodes, there has been great speculation about the potential for negative health impacts with consistent use.

However, few studies have focused on the direct link between antiperspirant use and cancer. Those that do have found no conclusive link between the two.

Many antiperspirants rely on aluminum to block sweat glands, as a way to reduce the amount of sweat released. Since aluminum is the active ingredient in many brands, some scientists have looked at the idea that aluminum may be absorbed into the skin through normal antiperspirant applications and razor cuts caused by shaving underarms.

One theory suggests that aluminum could cause changes in the estrogen (a hormone) receptors of breast cells. This may seem worrisome, because estrogen can promote the growth of cancerous and non-cancerous breast cells, but current studies have shown that it is not clear much aluminum can actually penetrate through the skin. One study found that only .012% of the aluminum chlorohydrate from antiperspirant application was absorbed. For reference, a person would usually absorb much more of this compound through the foods they eat than through antiperspirant use.

Another study found that women with breast cancer had no substantial difference in the amount of aluminum between the cancerous tissue and normal, non-cancerous tissues in their breasts.

According to the American Cancer Society, ingredients like aluminum most likely do not reach the body's lymph nodes and using antiperspirants does not cause toxins to be trapped within our bodies.

One note of caution, however: People with impaired kidney function are recommended to speak with their healthcare providers before using any products containing aluminum, even though the cancer risk is not the primary concern.

Parabens, also in anti-perspriants and other household products, are known to be absorbed through the skin but they have weak estrogen-like properties. We don't know if parabens are strong enough to cause changes in the breast cells. It is known that natural estrogens in the body are hundreds to thousands of times stronger than the estrogen-like properties in parabens. This is why the body's natural estrogens have been shown as a much likelier cause of breast cancer development than estrogen-like compounds from antiperspirants and other cosmetic products.

A small study found very small amounts of parabens in breast cancer samples. There was no link between the parabens as a cause of cancer, just that they were found in the breast tissue.

Similarly, 99% of people in a U.S. study were found to have some form of parabens in their urine; not just people with breast cancer.

The majority of people are exposed to parabens every day. Thus far, there have been no direct links between parabens and breast cancers.

Regardless, products containing parabens are required to list them as ingredients in most countries. However, most major antiperspirant brands do not contain parabens in 2021, unlike many other cosmetic and hygiene products.

According to the American Cancer Society, in the early 1990s, an email chain began to circulate a false rumor that underarm antiperspirants can cause breast cancer. Thirty years later in 2021, that claim is still frequently cited on social media today.

The close physical proximity between where breast cancers are primarily developed in the upper outer part of the breast, the lymph nodes, and the armpit where antiperspirants are applied is a likely reason for the major concerns about breast cancer and ingredients found in these products.

Additional concerns around the estrogen-like properties of aluminum or potential toxicity of parabens have also led to consternation about antiperspirant ingredients.

In addition, some chemical toxins like triclosan, phthalates, and propylene glycol frequently found in deodorants can alarm some users but have been deemed to be safe by national regulatory groups.

So far, however, there has been no direct causal link found between antiperspirant use, its chemicals, and the development of cancer. Studies have also since shown that aluminum antiperspirants will not increase cancer treatment-related skin irritation risks.

Claims about chemicals interacting with DNA with can lead to the formation of breast cancer in tissues have also been widely disproven.