It is taken once a week for one to two months. Tone evens out over that period, because after the rate of pigment formation slows, existing pigment needs that long to fade naturally. Stopping lifts the suppression and the tone returns to where it was.

It changes the environment in which pigment forms rather than removing pigment that already exists. It only interferes with the enzyme that makes pigment — it cannot break down what has already settled. It is used alongside laser toning to stop new pigment forming and hold the result.

A glutathione drip goes in intravenously and acts on the whole body. Brightening care applies ingredients directly to the skin and absorbs them, addressing tone in that area. For whole-body tone choose a glutathione drip; to concentrate on one area such as the face, brightening care — and the two are sometimes combined.