There are a number of arguments against the notion of sexual addiction. Some people think that an addiction must involve ingested substances. Recent studies in neuroscience are making this view out of date. We have become aware that certain activities can affect the brain chemistry in much the same way as recreational drugs. The brain chemistry of romantic attraction is a good example. It has all the characteristics of the effect of drugs of choice. For some people, exercise becomes an addictive process. For others it is food or shopping. Whatever the process, dopamine is released in the brain and dopamine is a key ingredient of pleasure. We can come to miss the dopamine high and seek to repeat it in distinctive ways.