Hydrolyzed milk protein is a mixture of peptides and amino acids derived from the enzymatic or acid breakdown of milk proteins, used in skincare and haircare to condition, hydrate, and form a smoothing film on skin and hair. It functions primarily as a humectant and surface conditioner rather than as a clinically proven active treatment.
| Reported effect | How often | Notes |
|---|---|---|
| Allergic contact dermatitis | Rare | Reported in individuals sensitized to milk proteins; may present as redness, itching, or eczema. |
| Contact urticaria | Rare | Hives at the site of application, particularly in people with milk allergy. |
| Skin irritation | Uncommon | Mild stinging or redness, often related to other formulation components. |
| Systemic allergic reaction | Very rare | Isolated case reports in highly milk-allergic individuals; theoretical risk from residual allergenic protein fragments. |
Frequencies reflect typical cosmetic use reported in the literature, not a guarantee for your skin.
Peer-reviewed papers on this ingredient, via PubMed.