Aluminium salts are the only known active ingredients which produce a strongly antiperspirant or sweat-restraining effect. But the highly efficient aluminium salts are always said to endanger your health. The claim that they would increase the risk of Alzheimer's disease has not been proved so far.
A correlation with breast cancer has also been repeatedly suggested. Recently, a researcher from the University of Geneva has discovered that aluminium chloride damages breast cells. Indeed, the aluminium chloride used in this study was injected directly into the cell culture. From a scientific point of view, the fact that the aluminium salts used in deodorants can never penetrate cells directly, and the skin anyway provides a natural barrier that prevents the penetration of these rather large molecules, render the results of this study more than questionable and practically irrelevant.
However, the sweat-restraining effect of the inorganic compound is established. Aluminium chloride acts as a stringent narrowing the sweat gland exit, which in turn very effectively reduces the sweat production. That's why aluminium salts are also prescribed by dermatologists in recipes against strong sweating, because they are the only active substance which has this effect.
Indeed, no pro without a con: aluminium chloride can irritate the skin and cause local reddening, itching and burning, especially when it is used several times a day. For this reason it is also recommended that antiperspirants should not be used more than twice a day. However, due to the long-lasting effect, applying it once per day is anyway enough.
Deodorants are more skin-compatible than antiperspirants because they only target the annoying odour of sweat. These deodorants prevent the formation of odours with ingredients like zinc ricinoleate, ethylhexyl glycerol or tri-ethyl citrate that reduce the germs which decompose sweat. For it is only the decay of sweat that produces unpleasantly smelling compounds which are responsible for the typical sweat odour.
Deodorant crystals are another option. They are based on the crystalline rock alunite or alum, which is, in chemical terms, potassium aluminium sulphate. It also belongs to the family of aluminium salts and can cause skin irritation. Alum has played a role in traditional healing, it has a blood-staining, astringent and antibacterial effect. In deodorants (e. g., crystal), it helps to close the sweat pores of the body, acting in the same manner as synthetic aluminium compounds.
If alum crystals are contaminated with pollutants or heavy metals, the skin-friendly property can be lost.
Conclusion: If you do not only mean to conceal unpleasant body odours more or less reliably but actually want to reduce your perspiration, you cannot avoid aluminium salts in deodorants. If you want to get deodorants without aluminium salt because of the media-induced panic, an intolerance to aluminium salt or injuries (from shaving), Belico Deo Spray II deodorant is your choice. You may also alternatingly apply both Belico deodorants, much reducing the amount of aluminium salts despite maximum effect.