Free flow of seburn and skin cells to the skin's surface is affected by an increase in hormone activity that causes the skin cells and seburn to stick together and block the pore.

The seburn and skin cells "plug" the neck of the pore and trap everything inside. The blocked pore (microcomedone) is the cause of every blockhead, whitehead, red pimple and pustule.

Because the pore is blocked P.acnes multiply quickly, thriving on the trapped sebum as a food source. Redness, puss and pimples are caused by the immune system which is trying to control the larger then normal number of P.acnes.