Acne is a change in the skin that comes about as the hormones start to kick in, producing changes in the body. The hormones will cause an increased output of oil from the oil glands on the face, and this oil is chemically different. Because it's chemically different, it affects the canal of the oil gland and causes the cells to become thicker in the gland. This can cause a blocking of the canal leading from the oil gland to the surface of the skin, and two things can happen. First of all, if the cells swell up enough that they just totally block the pore, then the oil can't get out and it will form what is called the whitehead. In other cases the canal from the oil gland gets narrowed down, and some of the oil gets caught and is exposed to oxygen, which turns it dark - and that's a blackhead that will plug up the pore. The oil can't get out and pressure builds up because it is still being produced in the gland. Bacteria that are normally present rupture in the surrounding skin and causes inflammation, and that causes a zit or a pimple. It's not really an infection; it's a condition of the skin produced by the changing hormones. It is something that can be treated with a fair degree of success if patients understand what's going on.
