Natural deodorants: aluminium, alum and other ingredients - what is the difference?

Sweating is a natural and essential function plays a vital role in regulating body temperature and maintaining the body’s natural balance. Sweat itself is virtually odourless; body odour develops when it interacts with the bacteria naturally present on our skin.

For this reason, deodorants have become an essential part of many people’s daily hygiene routine. In fact, the importance of this category is reflected in its continued growth: the Spanish deodorant and antiperspirant market was valued at more than €335 million in 2023, after growing by 8.24% compared with the previous year[1]. However, not all deodorants work in the same way. While some are designed to reduce perspiration temporarily, others help control odour-causing bacteria or absorb moisture while allowing the skin’s natural sweating process to continue.

Growing interest in natural cosmetics has popularised terms such as aluminium-free, alum crystal and mineral-based ingredients. But what do these claims mean? Is a deodorant the same as an antiperspirant? And how do aluminium salts, alum and ingredients such as bicarbonate or magnesium differ?

Deodorant or antiperspirant?

One of the most common misconceptions when choosing a product for underarm care is assuming that all deodorants work in the same way.

Deodorants primarily control body odour. They do not stop the natural process of sweating, but instead help reduce the smell that develops when sweat interacts with the bacteria naturally present on the skin, by targeting odour-causing bacteria, absorbing moisture or providing fragrance.

Antiperspirants, on the other hand, are formulated to reduce perspiration. They typically contain aluminium salts, which dissolve in sweat and form a gel-like structure within the sweat ducts, reducing the amount of sweat reaching the skin’s surface. This effect is temporary, as perspiration remains an essential physiological process.

Understanding this distinction helps consumers choose a product according to their needs: whether they want to reduce visible moisture or simply maintain freshness while allowing the skin’s natural sweating process to continue.

Aluminium in deodorants

In cosmetics, “aluminium” refers to aluminium salts, such as aluminium chlorohydrate or aluminium chloride, rather than pure aluminum metal. Their role is to temporarily reduce sweating: when applied, they dissolve in sweat and form a temporary gel-like plug limiting sweat flow through the ducts.

The safety of aluminium salts has been widely discussed, particularly regarding possible links with health issues, including breast cancer or neurological conditions.

Some observational studies have explored aluminium levels in human tissues, including breast tissue[2]. However, regulatory scientific assessments have not established a causal link between the use of aluminium-containing antiperspirants and these health concerns when products are used as intended.

As with any cosmetic ingredient, individual tolerance can vary. In some cases, aluminium-containing antiperspirants may cause irritation or sensitivity, particularly for people with reactive skin or when applied after shaving. Some dermatologists may also recommend adjusting their use for people with certain skin conditions, such as atopic dermatitis, or during periods when the skin barrier is more vulnerable, including breastfeeding[3].

Ultimately, choosing an aluminium-containing antiperspirant or an aluminium-free deodorant is a personal decision based on individual needs, preferences and expectations.

Alum: a mineral alternative to conventional antiperspirants?

Alum, often known as “alum crystal” or “mineral deodorant”, is a popular alternative in the natural deodorant category. It has been used for centuries for its astringent properties and remains popular among consumers looking for a more mineral-based approach to underarm care.

Despite sometimes being marketed as an “aluminium-free” alternative, alum is a naturally occurring mineral salt that contains aluminium. The most commonly used form in cosmetics is potassium alum (potassium aluminium sulphate), a compound made up of potassium, aluminium and sulphate.

Unlike conventional aluminium salts, alum does not significantly reduce perspiration. Instead, it mainly acts on the skin’s surface, helping create an environment less favourable for odour-causing bacteria while allowing the natural process of sweating to continue.

This is why alum-based deodorants should not be considered equivalent to antiperspirants containing aluminium salts: while antiperspirants are designed to reduce perspiration, alum-based products focus primarily on controlling body odour without significantly altering sweat production.

Other common ingredients in natural deodorants

Many natural deodorants rely on a combination of ingredients that do not stope perspirateion but help control body odour, absorb moisture or provide a pleasant sensory experience.

• Sodium bicarbonate: neutralises unpleasant odours by modifying the skin’s pH, creating an environment less favourable for odour-causing bacteria. However, its alkaline nature may cause irritation in some sensitive skin types.
• Magnesium hydroxide: helps control odour without blocking the natural sweating process and is often considered a gentler alternative for bicarbonate.
• Starches and absorbent powders: such as arrowroot powder, tapioca or corn starch help absorb moisture and provide a drier sensation on the skin, without preventing perspiration.
• Essential oils and botanical extracts: provide fragrance and contribute to odour control through their antimicrobial properties. However, individual sensitivity should be considered.
• Zinc-based ingredients: such as zinc ricinoleate or zinc oxide, can help reduce unpleasant odours by capturing molecules responsible for body odour.

 How to choose a deodorant?

There is no single deodorant that is ideal for everyone. The right choice depends on individual needs, level of perspiration, skin sensitivity and personal preferences. Understanding the role of each ingredient helps consumers make more informed decisions and have realistic expectations about what each formula can achieve.

As a general guide: 

Ultimately, choosing a deodorant is a personal decision. The key is understanding how different ingredients work and selecting a product that best matches individual needs and expectations.

Article written by Paula Gómez de Tejada, NATRUE Global Communications and Public Relations Manager, and Aida Martínez, Certification Manager at NATRUE. 

Originally published on Bio Eco Actual (available here in Spanish.)

References:

[1] https://www.globaldata.com/store/report/spain-anti-perspirants-and-deodorants-market-analysis/

[2] https://pubmed.ncbi.nlm.nih.gov/17629949/

[3] https://angelicadominguez.com/desodorantes-con-aluminio-y-cancer-mito-o-riesgo-real/