Salicylic Acid

INCI - Salicylic Acid.

What is it - Salicylic acid is a beta hydroxy acid (BHA) an active used in cosmetic formulations for its exfoliating, anti-inflammatory, and acne-fighting properties. It works by penetrating into pores, helping to clear excess oil and dead skin cells, making it ideal for oily and acne prone skin.

pH - Formulate to below 3.0 to be 50% bioavailable.

Safety limit - Up to 0.5% in body lotions, eye shadow, mascara, eyeliner, lipstick, roll on deodorants and if used as a preservative. Up to 3% for rinse off hair products and 2% for other products.

Formulas used in - Serums, lotions, creams, shampoos.

Formulation notes - Salicylic acid is notoriously difficult to work with. It is insoluble in most substances and is prone to recrystallising in finished formulas over time. Stability and pH should be carefully observed. Check individual safety data sheets (SDS) with specific suppliers usually section 9 physical and chemical properties it will tell you the solubility of that particular grade of salicylic acid. Otherwise as a general guide use 1:10 salicylic acid to propylene glycol ratio. For example, 1% salicylic acid and 10% propylene glycol.

Odour - Odourless.

Form - Fine white crystals.

Heat sensitivity - Heat stable when formulating however will degrade in finished formulas over time if exposed to heat.

Solubility - Insoluble in water and oils, highly soluble in ethanol.

Natural / synthetic status - Naturally occurring however it is generally synthetically produced for cosmetic use.

Contraindications - Salicylic acid should not be used on broken or irritated skin as it can make irritation worse. It can also cause dryness or redness for those with sensitive skin. People with an aspirin allergy should avoid it, as it may cause a reaction. It should not be used in products intended for children under 3 years old. Be careful when using it with other strong ingredients like retinoids or benzoyl peroxide because it may cause irritation.