What used to relate purely to ingredients that qualify as drugs, is now used as a marketing tool industry-wide and to say that the terms 'active' and 'inactive' are overused and abused by marketing departments everywhere is an understatement.
Active ingredients - traditionally, when used in products considered drugs i.e. SPF products - are 'any component of a drug product intended to provide therapeutic and pharmacological activity in direct effect to a diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body of humans.'
Depending on your country, retinoids, acids, sunscreens like oxybenzone and avobenzone are all considered 'active'.
They are considered active enough to change the structure of the skin. Take prescription strength retinoids. In a product like that, the vitamin A will be classed as the drug and therefore 'active' and the rest of the ingredients are 'inactive' because they make up the formula/emulsify/are the delivery system and do not actually change the structure of skin at all. A lot of ingredients considered truly 'active' will have a maximum % that they are allowed to be used at in any formula.
Inactive ingredients - officially, are 'any component of a drug product other than the active ingredients.'
However, we are now seeing the words 'active' and 'inactive' bounded about everywhere as the general rule, not the exception to be used only in the case of drugs.
A brand will say 'active' ingredients are peptides, vitamin c, seaweed, whale sperm, witch's warts...pick something. What they actually mean when they say this is 'what we are charging you the big bucks for'.
Inactive ingredients are all too often completely glossed over, ignored or relegated to the very smallest font on the pack and except in the rarest of circumstances, essentially mean 'the bulk of the product' i.e. water/carrier oils etc.
The potential problems arise when unknowing customers purchase something assuming that 'inactive' means 'has no effect on the skin'. Just because something doesn't change the structure of the skin ('active') does not mean that something does not affect the skin.
Alcohol, fragrance and silicones, for example, are all 'inactive' ingredients, yet the ones I am asked about the most from readers. You can bet that a high level of alcohol in a product will be 'active' on your skin in some way.
If a bacon sandwich was skincare, the bacon would be labelled on the pack as the 'active' ingredient, but the bread would certainly be an active ingredient to someone with a gluten intolerance or a wheat allergy.
Ignore the marketing hype, read the ingredients label. That's where you see what is likely to be an 'inactive' ingredient that could actually be something 'active' for you to look out for.
Some brands have started using bold type for their 'active' ingredients in their inci lists in order to make them stand out. Clever, but not if you know what you are looking at.
Tomorrow: how to read an ingredients label.