Addiction is a condition that results when a person ingests a substance e.g. alcohol, nicotine or engages in an activity e.g. gambling, sex, shopping that can be pleasurable, but the continuation of which becomes compulsive and interferes with ordinary responsibilities such as work, relationships and/or health. People who have an addiction may not be aware of their behaviour which is out of control and causing problems for themselves and others. Addiction to substances or activities can sometimes cause serious problems at work, home or in relationships. The causes of addiction vary and can be a combination of physical, mental, circumstantial and emotional factors.