IFRA Restrictions

The International Fragrance Association (IFRA) publishes restrictions on how much of certain materials can be used in fragrance — typically driven by skin-sensitization or allergen concerns. Oakmoss, real ambergris, and several other classic materials have been restricted over the years, which is why old reformulations of fragrances (like the original Chanel No. 19 or Mitsouko) smell different from modern versions: the perfumer was forced to substitute materials. This isn't a conspiracy — IFRA limits are usually backed by allergy data — but it does mean that vintage hunting in fragrance is a real thing, and reformulations get scrutinized closely by community.