The banning within the last decade of methylisothiazolinone (MI) and methylchloroisothiazolinone (MCI) in leave-on cosmetics (e.g. moisturisers, make-up, deodorants) in Europe, Canada and Australia has seen a reduction in sensitisation and ACD caused by these two preservatives — with no such reduction seen in America, where MI and MCI remain permitted.
But many in the isothiazolinone allergy community continue to assume this important legislative shift refers to all consumable products and preparations which are applied to the body and ‘left on’.
It does not.
it refers to leave-on cosmetics only.
What is a cosmetic?
Many wrongly assume the word ‘cosmetic’ refers only to make-up.
It is broader than that.
A cosmetic is any preparation applied to the skin, hair or oral cavity for the purposes of moisturisation, conditioning, cleansing, deodorising, fragrancing, sun protection or colouring.
That means body lotion, shower gel, toothpaste, mouthwash, anti-perspirant, perfume, hair dye and shampoo are all examples of cosmetics.
Some of these are not ‘leave-on’ products, but ‘rinse-off’ products, which are washed away.
There is no full ban in ‘rinse-off’ products, so you may find MI/MCI in some shower gels and shampoos, for example.
What is not a cosmetic?
Some products applied to and left on the body, then, are not cosmetics, and may potentially contain MI.
Here are some examples:
Muscle / joint / massage oils and balms
Medical ointments and infused patches
Intimate lubricants
Mosquito sprays
Here is an example of an intimate sex lubricant, designed to stimulate the clitoris, which contains MI and MCI, sold in the UK.
And here is evidence of a case report into a haemorrhoid cream containing MI and MCI, used in Europe.
Both extreme examples, granted, but chosen unapologetically with the intention to shock.
What may or may not be a cosmetic?
In some cases, it may not be obvious whether or not a product is a cosmetic.
The best example is of a hand sanitiser.
If a hand sanitiser’s only job is to sterilise / protect from germs, then it is not a cosmetic.
But if a hand sanitiser also contains a moisturising element, and is dual-purpose hand cream and hand sanitiser, for example, then it might be classed as a cosmetic for legislative purposes, and formulated to meet cosmetic regulation.
Eye drops, theoretically, may be another. Are the eye drops to relieve irritation (non-cosmetic) or are they to brighten your eyes (cosmetic)?
A product to treat acne? Not a cosmetic. A product to conceal acne? Cosmetic.
In all such cases, care must be taken.
Language matters
Although I don’t always like language policing, it is important we aim to be pedantic and strict with the meanings of words and definitions to avoid ambiguity and confusion.
Where the laws apply, MI and MCI are banned in leave-on cosmetics not all leave-on products, and we must continually remind ourselves of it, especially for the sake of the newly diagnosed.