Purging

Purging is a temporary worsening that happens when an ingredient speeds up how fast skin sheds its surface cells. Congestion that was already forming beneath the surface comes up sooner than it otherwise would.

Only ingredients that affect cell turnover can cause it: retinoids, AHAs, BHAs and benzoyl peroxide. A moisturiser, a hydrating serum or niacinamide cannot purge you. If one of those breaks you out, it is a reaction to the product, not purging.

How to tell the difference:

- Purging appears in the places you normally break out, surfaces quickly, clears quickly, and settles within four to six weeks. - A reaction appears in new places, often as small uniform bumps or itching, and does not settle.

Six weeks is the limit of reasonable patience. Longer than that is not purging; it is a product that does not suit you.

The practical advice is to introduce one active at a time and reduce frequency rather than stopping — a retinoid at one night a week is still a retinoid, and most people who 'cannot tolerate' one simply started at four nights.