Woolmark discusses a scientific review of claims that wool causes allergy, distinguishing an immune reaction from mechanical irritation. Coarse fibres projecting from a fabric can press against the skin and create itch or prickle. The review notes that this mechanism can also occur with coarse synthetic fibres.

Prickle From Coarse Fibres Is Different From an Allergy Diagnosis

Fine Merino bends more readily, helping explain why one wool garment may feel different from another. Persistent skin symptoms still need individual assessment rather than a diagnosis from a fabric label. The useful textile distinction is between fibre diameter, the sensation it creates and an actual allergic condition.