When it comes to your skin, it needs both oil and water to maintain balance and youth. We do this by replenishing lubrication (oil) AND moisture (water) after cleansing the skin.
Remember that the skin is an organ. When skin is lacking oil or lacking moisture it will do whatever it takes to balance out, just as any other organ in the body would. In this case it will produce more oil to compensate for the loss, hence, twice the amount of oil pumped out of each pore and the end result being, a congested pore. Voila, a pimple!
Keep in mind that while oily skin requires more maintenance to keep it balanced, oil is not the enemy. The more oil, the less wrinkles 🙂