Aluminium chloride and sodium hydroxide: why mixing matters

Sodium hydroxide may appear in a manufactured formula as a controlled pH adjuster, but that does not make household sodium hydroxide suitable for adding to an aluminium chloride antiperspirant. Use the finished product exactly as supplied.

Aluminium chloride solutions are acidic, while sodium hydroxide is strongly alkaline in concentrated forms. Combining them changes the chemical environment and can produce aluminium-containing solids rather than simply making a gentler version of the original solution.

Manufacturers control ingredient grade, order of addition, concentration, and final pH. An ingredient list describes the finished formulation; it is not a recipe for combining raw ingredients or separate skin products.

Keep each chemical in its original labelled container and away from children. Never use drain cleaner, laboratory chemicals, or household alkali to alter an antiperspirant. Do not apply raw sodium hydroxide to skin because it can cause a chemical burn.

For a prepared aluminium chloride product, apply only to intact, dry skin at the directed site. If it irritates, stop using it and consult the pharmacist or prescriber about a different strength, vehicle, or schedule instead of trying to neutralise it yourself.

After skin contact with sodium hydroxide or an unknown mixture, remove contaminated clothing and rinse the exposed skin immediately with plenty of running water. Do not put another chemical on the area to neutralise it, because further reaction can add heat and injury.

Seek urgent medical assessment for persistent pain, whitening or darkening of skin, blistering, an eye exposure, trouble swallowing, breathing difficulty, or any ingestion. Bring the product container or label if this can be done safely, as the exact substance helps clinicians guide care.

Show your clinician or pharmacist the complete label and ask whether sodium hydroxide is part of the finished formula, which body sites are appropriate, and how to handle irritation. If the substances were mixed accidentally, describe what was combined, the route of exposure, and the skin or eye changes you notice.