For years, warnings have circulated that using underarm deodorant may lead to breast cancer, especially if the product contains aluminum or parabens, or if used immediately after hair removal.

Some rumors go further, claiming that antiperspirants "clog pores" and prevent the body from eliminating toxins, which over time turn into tumors.

But this frightening picture does not reflect what science has found so far.

Deodorant and Cancer

The claim that deodorant or antiperspirants cause breast cancer, for example, is a myth unsupported by available evidence, and no reliable studies have proven a causal relationship between regular use of these products and cancer.

The latest meta-analysis of studies, published in 2024, concluded that there is no increased risk of breast cancer from using deodorant or antiperspirants.

However, it remains scientifically legitimate to study long-term exposure to certain ingredients, especially since most available human evidence comes from a limited number of observational studies, not experiments designed to prove causation.

These concerns originally stemmed from some laboratory studies suggesting that aluminum may interfere with estrogen signaling or affect breast cells.

Estrogen is indeed capable of stimulating the growth of some hormone-sensitive types of breast cancer.

But the U.S. National Cancer Institute confirms that studies "have not shown any substantial adverse effects of aluminum used in antiperspirants that can be linked to an increased risk of breast cancer."

Harms of Deodorant

A comprehensive scientific review in 2014 found no clear evidence that underarm preparations containing aluminum increase risk.

The European Scientific Committee on Consumer Safety concluded that aluminum exposure from daily use of cosmetic products does not significantly add to the total body burden from other sources, primarily food.

The committee considered aluminum compounds safe in non-spray deodorants and antiperspirants up to a concentration equivalent to 6.25% aluminum, and in spray products up to 10.60%.

This assessment does not mean that every amount of aluminum is safe under any circumstance, but that cosmetic use within the evaluated limits and formulations has not been shown to pose an unacceptable risk.

Causes of Breast Cancer

After a series of previous studies, researchers in 2024 pooled results from 7 case studies examining antiperspirant or deodorant use and breast cancer risk.

The analysis found no statistically significant difference between users and non-users.

If these products were a major cause of breast cancer, the analysis would have shown a consistent and clear increase in risk across different studies, which did not happen.

However, the degree of heterogeneity between studies was about 60%, and the analysis relied on both old and new observational studies that differ in defining and measuring use. Therefore, it cannot prove 'zero risk' absolutely, but it provides the strongest available summary of human studies and does not support the claim that regular use increases breast cancer.

Parabens: The Worrisome Substances

Parabens are a group of preservatives that prevent bacterial and fungal growth in cosmetics. Cell experiments have shown that some types can mimic estrogen activity, though their potency is usually much weaker than the natural hormone.

A study that detected traces of parabens in breast tumor samples caused widespread concern, but detecting a substance in a tumor does not mean it caused it; substances can reach tissues after exposure from multiple sources, and these studies do not reveal when the substance entered, from which product it came, or whether it preceded tumor development.

The U.S. National Cancer Institute says that despite finding parabens in some breast tumors, there is no evidence they caused cancer. Moreover, most deodorant and antiperspirant products on the U.S. market no longer contain parabens.

Common Cancer Myths

Antiperspirant reduces sweat in a limited skin area through temporary plugs inside sweat ducts; it does not block the lymphatic system, clog deep underarm lymph nodes, or prevent them from performing their immune function. Using it under the arms does not stop sweating elsewhere in the body.

There is no human evidence that reducing underarm sweat leads to retention of carcinogens in breast tissue. The National Cancer Institute explicitly classifies the claim that antiperspirants or deodorants cause breast cancer as a "common myth" about cancer.

However, U.S. Food and Drug Administration instructions advise not applying antiperspirant to broken skin and discontinuing use if rash or irritation occurs, to protect the skin and reduce absorption and inflammation—not as an admission that the product causes cancer.

Deodorant and Mammography

Radiology centers typically ask women not to use deodorant, antiperspirant, powder, or creams under the arms or on the breast area on the day of a mammogram for breast cancer screening.

Some ingredients in these products may appear as small white spots on the X-ray image, potentially interfering with interpretation or resembling calcifications that radiologists look for.

Kidney Patients and Antiperspirants

U.S. regulations require manufacturers of antiperspirants containing aluminum to include a statement asking people with kidney disease to consult a doctor before use. Warnings also include not applying the product to broken skin, discontinuing use if rash occurs, and avoiding inhalation of sprays.

According to scientific studies, this warning does not mean antiperspirant causes kidney failure or cancer in healthy individuals; it is an important precaution for those with advanced kidney impairment, as their ability to process and eliminate certain substances may be compromised, especially when using high-concentration medical products for hyperhidrosis.

While evidence does not support a cancer risk, these products can cause real skin problems.

Natural Deodorant

The word 'natural' is not a medical guarantee of safety, and the phrase 'aluminum-free' does not mean the product has been proven to reduce cancer risk.

Natural deodorants may contain baking soda, essential oils, or plant extracts, which can irritate or cause allergies in some users.

Also, some products known as 'crystal' contain alum salts, which are compounds that include aluminum in their composition, despite sometimes being marketed as aluminum-free alternatives.

Tips for Choosing Deodorant

Those who do not suffer from excessive sweating and simply want to reduce odor can choose a deodorant without antiperspirant ingredients. Those who sweat heavily can use an antiperspirant containing an aluminum salt, from a well-known and registered product, following instructions and avoiding overuse.

For sensitive skin, it is preferable to choose a product labeled 'fragrance-free' rather than 'unscented'; because unscented products may contain fragrance materials intended to mask the smell of other ingredients.

The American Academy of Dermatology recommends testing the product on a small area and discontinuing use if a rash or persistent itching appears.