The science
The chemistry that matters most here is the difference between a soap and a syndet, because this wash is mostly the former. Soaps are the alkali salts of fatty acids, made by reacting fats with a strong base; this formula lists potassium cocoate, potassium palm kernelate and potassium shea butterate, which are pre-made soaps, and also potassium hydroxide alongside stearic, myristic and coconut acids, which saponify in the tube to make more. The result is a wash with a pH well above the skin's own 4.5 to 5.5. Alkaline cleansing removes sebum efficiently, which is why oily skin feels so clean, but it also solubilises more of the stratum corneum's own lipids, swells corneocytes and transiently raises skin pH, effects that studies of soap versus synthetic detergent cleansers have consistently linked to greater dryness, tightness and irritation in normal and dry skin. The sodium methyl cocoyl taurate and decyl glucoside present are mild syndets that soften the blend, but they are outnumbered.
The exfoliation is well designed. Jojoba esters are hydrogenated jojoba wax formed into smooth spheres; unlike angular nut-shell or pumice particles they roll over the surface, and their friction is low enough that the mechanical exfoliation is superficial, loosening corneocytes and comedonal debris without abrading. They are also biodegradable, which is why they replaced polyethylene microbeads after the 2015 US ban on plastic microbeads in rinse-off cosmetics took effect.
The acne actives are where the label outruns the formula. A 2007 randomised, double-blind, placebo-controlled trial in the Indian Journal of Dermatology, Venereology and Leprology found that a 5 percent tea tree oil gel applied as a leave-on for 45 days reduced total acne lesion count and severity significantly more than placebo in mild to moderate acne, with the effect attributed to terpinen-4-ol's antimicrobial action. That evidence does not transfer to a rinse-off at an undisclosed concentration and thirty seconds of contact. Salicylic acid is an FDA monograph acne active at 0.5 to 2 percent, but this product carries no drug facts panel, so it is included below that range as a cosmetic ingredient; moreover, salicylic acid penetrates lipid-filled pores in its un-ionised form, which predominates at acidic pH, and in an alkaline soap most of it is ionised and inactive. Tamarind extract, willow bark, black cumin and mango seed oil are botanical passengers with no clinical data at rinse-off exposure. SheaMoisture publishes no efficacy testing of the wash.
References 1 ShowHide
- The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study — Indian Journal of Dermatology, Venereology and Leprology (2007)