There is no consensus in the medical community that sexual addiction actually exists.
The behavior of sex addicts is comparable to behavior of alcoholics and addicts, where sex functions like a drug. A common definition of alcoholism is that a person has a pathological relationship with this mood altering drug.[1] It provides a quick mood change, works every time and the user loses control over their compulsion.[2] Like alcoholics, sex addicts' lives rotate around the constant desire for their "drug" of choice.
The Mayo Clinic uses compulsive sexual behavior for sexual addiction, and defines it as "an overwhelming need for sex and are so intensely preoccupied with this need that it interferes with your job and your relationships. [...] You may spend inordinate amounts of time in sexually related activities and neglect important aspects of your day-to-day life in social, occupational and recreational areas. You may find yourself failing repeatedly at attempts to reduce or control your sexual activities or desires."[3]
According to Counseling Affiliates, an addiction is at work when sex becomes shameful, secret, or abusive.
The Society for the Advancement of Sexual Health further illustrates addiction by outlining several key components: "Compulsivity, that is, loss of the ability to choose freely whether to stop or to continue; Continuation of the behavior despite adverse consequences, such as loss of health, job, marriage, or freedom; Obsession with the activity."
http://en.wikipedia.org/wiki/Sexual_addiction