Persulfates (ammonium, potassium, sodium persulfate)

What it is

Persulfate salts are added to hydrogen peroxide in powder bleaches, mostly professional products. They are cosmetic ingredients that act as respiratory and skin sensitisers.

How it works

Persulfate adds to the oxidative bleaching of melanin and keratin described under hydrogen peroxide. Model-bleach work shows persulfate also reacts with additives in the formula, such as the diamine used in Olaplex. Gargano 2018 Ammonium persulfate activates mast cells and basophils in the lab, which is thought to be relevant to hairdressers' asthma.

What the studies show

• A multicentre cohort of 107 hairdressers and others with persulfate occupational asthma, confirmed by inhalation challenge, found longer exposure before onset than in asthma from other agents. 76% had work-related rhinitis, and isolated late reactions were more common. Doyen 2025

How it's used in studies

It is used inside salon lightener powders and has not been studied as a stand-alone treatment.

Side effects and safety

Serious for hairdressers: occupational asthma and rhinitis, plus allergic contact dermatitis and hives. Clients are exposed briefly, but powders used at home in unventilated bathrooms are a worry. Use dust-free (granulated or encapsulated) products, ventilation and gloves.

Bottom line

Not an ingredient to seek out. If you bleach at home, avoid inhaling powder and prefer low-dust products. Stylists should use ventilation. We are confident in the hazard. Whether persulfate-free lighteners lighten as well was not reviewed. See bleach and colour damage.