Leave on versus rinse off: a clear cosmetic distinction?

Is it obvious to you what the difference between a “leave on” and a “rinse off” or (“wash off”) product is? 

The distinction matters when it comes to MI / MCI in some countries, because MI has been banned in so-called leave on products in the UK and EU — but is still permitted at low levels in so-called rinse off products.

Here is the EU definition:

Clearly, then, a shower gel is a rinse-off product, and a face cream is a leave-on product.

But what about a bath oil? You pour it into the bath, and you get into the bath and you may stay there for some time — especially if your muscles are in need of relaxation or you like to use bath time as thinking or ‘down’ time. Does that count as ‘prolonged contact with the skin’? 

And what about a foot soak? Recently a new product was launched by Marks and Spencer in the UK. The Bare Feet by Margaret Dabbs Soothing Foot Soak may well be soothing to non MI-allergics, but will be far from soothing if you have MI allergy — as it contains both methylisothiazolinone and methylchloroisothiazolinone as preservatives. 

To my mind, there are two concerns here:

The first, a foot soak could be easily considered a ‘leave on’ product — and therefore mistakenly considered automatically safe by a consumer in one of the countries where MI / MCI have been banned in leave-on products. 

The second, the risk of sensitisation to MI to a non-allergic individual, caused by the kind of prolonged contact which is likelier to cause the ingredients to penetrate the skin. Shower gel will only stay in contact with the skin for seconds before being washed and flushed away — insufficient time to do any damage to someone not sensitised. But the ingredients of a foot soak could be in contact with the skin for half an hour or more — especially if the product is so soothing you nod off. Is there a realistic risk? Have scientists considered this?

As always, it pays to double check the label, every time. Never assume, never take anything for granted. 


  1. blp

    A rinse-off or a leave-on is all the same to my skin. Since developing this allergy this summer, Dawn soap, Bath and Body Works soap and also the hand soap at the school where I work all very much aggravate, irritate redden my skin. These are not leave-ons, but I have quit using all of them and anything else that is even closely related to MIT.

  2. bonnie

    Rinse-offs and Leave-ons both irritate my skin. I STAY away from all of them as much as I can!!


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