Ammonium Lauryl Sulfate.

What it does

It is chemically close to the harsh-reputation SLS, but the ammonium counter-ion makes it somewhat milder. Its irritancy is concentration-dependent, and it is a cleansing agent rather than a leave-on skin active.

Benefits

• Effective cleanser that dissolves both oily and water-based soils
• Creates a creamy, luxurious, high-foam lather
• The ammonium form is milder than its close relative SLS
• Generally regarded as safe in brief, rinse-off use followed by thorough rinsing

Side effects

• Irritation is concentration-dependent: below about 1% it is essentially non-irritating, but above ~10% it can cause moderate to strong irritation
• Can be drying and may cause scalp itching, eye irritation, or, rarely, allergic reactions
• Best limited to short-contact, rinse-off products rather than prolonged or leave-on use

Who it's for

Normal to oily skin and general body or hair cleansing where a rich foam is wanted, in well-formulated rinse-off products