Common Name(s): Magnesium lauryl sulfate,divalent mg²⁺ counterion surfactant,gentle anionic

CAS Number: N/a

DESCRIPTION

What It Does: Magnesium lauryl sulfate provides anionic surfactant cleansing and foam with gentler skin interaction than the sodium equivalent — the divalent mg²⁺ counterion pairs with two anionic head groups simultaneously forming a tighter ion pair that reduces the freely-available negative charge at the micelle surface, moderating the protein denaturing activity responsible for skin irritation.

Why It's Used: Formulators choose magnesium salts of anionic surfactants to achieve improved skin tolerance versus sodium equivalents without changing the hydrophobic chain chemistry. the mg²⁺ divalent counterion shielding of the anionic head group provides a measurably gentler skin interaction profile. mg²⁺ also provides beneficial ionic supplementation to formulations where magnesium skin conditioning is desired — mg²⁺ ions support skin barrier enzyme function (including serine protease regulation and ceramide synthase activity) at the low concentrations present in surfactant systems.

How It Works: Magnesium lauryl sulfate functions through the double counterion pairing unique to divalent metal salts of anionic surfactants: monovalent na⁺ forms a loose, hydrated ion pair with each individual sulfate or sulfonate head group leaving the negative charge largely exposed (bjerrum length < interion distance at typical ionic strength). divalent mg²⁺ (charge +2) can simultaneously interact with two anionic head groups from adjacent micelle-surface molecules — the double ionic interaction creates stronger ion pairing that reduces the electrostatic potential at the outer micelle surface. the reduced negative surface potential at the micelle-solution interface decreases the electrostatic driving force for protein binding, explaining the documented reduced protein denaturation and lower skin irritation. the mg²⁺ salt also has different solubility and physical properties from na⁺ equivalents — often higher aqueous solubility at cold temperatures from the hydrated mg²⁺ disrupting crystal packing.

Typically Found In: Gentle anionic cleansers,sensitive skin formulas

TECHNICAL DETAILS

Primary Category: Active ingredient – cosmetic active

Secondary Functions: Skin conditioning

Application Areas:

Typical Concentration Range: 3%–20%

SOURCING & ETHICS

Vegan Status: Conditional - supplier confirmation required

Halal Status: Unverified - supplier confirmation required

Source Notes: Commercially produced for cosmetic use. verify vegan/halal status with supplier. [audit 2026-07-29 rev2: the record's own source_notes does not assert a non-animal origin, or instructs the reader to verify with the supplier; "yes" asserts knowledge the record does not hold. determination requires shariah-panel sign-off.]

SKIN COMPATIBILITY

Irritancy Rating: 1/5 – very low

Comedogenicity Rating: 0/5 – non-comedogenic

Sensitivity Concerns: Well-tolerated by most skin types.

Safe for Sensitive Skin: Yes

SAFETY & COMPATIBILITY

Safety Profile: Good safety profile at recommended concentrations. ewg score: 1–2.

Works Well With: Standard skincare actives

Avoid Combining With: No known significant incompatibilities

SCIENTIFIC NOTE

Divalent counterion bridge mechanism: mg²⁺ has an ionic radius of 0.72 å vs na⁺ (1.02 å) — smaller but with 2× the charge, providing a charge density of +2/0.72 = 2.78 vs na⁺ +1/1.02 = 0.98. the much higher charge density drives stronger electrostatic interaction with anionic surfactant head groups. at a micellar surface, mg²⁺ bridges two adjacent sulfonate/sulfate groups through bidentate coordination — one mg²⁺ neutralising two negative charges rather than one, halving the effective surface charge density. this charge neutralisation from bridging provides the gentleness mechanism unique to divalent counterion surfactants.

Last Verified: 2026-03-12

Primary Sources: Cosing database,magnesium counterion surfactant gentle skin review