Oily skin overproduces sebum, often because of hormonal changes or imbalances.  

Sebum: a natural oily substance within the skin that helps to hydrate and protect it.  

It might surprise you, but dehydration can also cause the overproduction of sebum.  

This is a natural reaction of the skin, to try to compensate and hydrate itself.  

The result is excess shine, sometimes a greasy feel to the touch, and visibly enlarged pores.  

With all the excess oil blocking pores, oily skin is most prone to blemishes such as spots and blackheads.  

How to look after this skin type: when it comes to your skincare routine, opt for lightweight moisturisers and double cleanse with clarifying cleansers to deeply cleanse the pores and avoid build up.