This one might seem a bit obvious, but it's an important one to mention. If you already have oily skin, you don't want to add more oils to it in order to remove makeup. Since your skin is already producing extra sebum, you're in danger of clogging your pores, which can lead to acne [source: WebMD].
Without oils, makeup removers use other ingredients that don't add additional grease. Some might even dry out your skin a bit. Examples of what you might find on the ingredients listing include water, benzyl alcohol, aloe and cyclopentasiloxane, an emollient which actually adds moisture and increases the capacity for your skin to hold water [source: Starch]. Although moisturizing oily skin might seem backward, some cleansers can actually strip away too much necessary sebum, so adding back moisture can help your skin.
If you need to get deep down and clean up more than just your skin's surface, you might want to consider another type of makeup remover, which we'll be looking at in the next section.