Reformulation

Products are not fixed objects. A supplier stops making the grade a formula uses. An ingredient becomes unusable in one market and the brand would rather run one recipe than two. A stability problem surfaces a year after launch. Any of these changes the formula and leaves the branding alone.

The feel gives it away before the label does — a thinner slip, a different dry-down, a fragrance close but not the same. The check is the list on the new pack against a photograph of the old one — a good reason to take that photograph. One false alarm: the same brand's product is often built differently for different markets, because what is permitted is decided locally — a bottle bought abroad can differ with nothing reformulated.

It matters most to anyone with a reaction history. Something you used happily for two years is, after a reformulation, a product you have not tried. Read the list again and patch test it as you would anything new; a reaction is worth taking to a clinician rather than working out by elimination on your face.

Reformulation is often an improvement: a better preservative system, an allergen taken out, a filter that lasts longer in light. New and improved is sometimes true. Same great formula, on a box whose ingredient list has changed, is not: the list has to keep up with the formula, everything else on the pack can stay as it was.