It depends upon the material of the cupholder. Cup holders made up of copper, aluminium, steel, or any other material susceptible to corrosion might corrode. So, it is safe to choose materials resistant to corrosion, such as stainless steel, plastic etc. Corrosion happens when any material reacts with oxygen, hydrogen and even dirt, debris and bacteria. Hence, pay extra attention while choosing any bathroom accessory, be it a towel hanger or a cup holder. It helps you choose the right.