Addiction is the dependence on a particular substance, to the extent that fulfilling that dependence becomes a dominant preoccupation in a person's life. Addictions may be physical, in that the withdrawal of the substance produces symptoms such as diarrhea and vomiting, or the dependence might be more psychological, producing craving and agitation if the consumption of the substance or behavior is prevented. Substance misuse, involving drug and alcohol abuse is an increasing international problem. These misuses cause a range of health and social problems, including the breakdown of families and increased levels of crime. Addictive behavior, such as compulsive gambling or shopping, causes social problems more than physiological problems.

Drug addicted people who have difficulty in dealing with anxiety, stress and other emotional issues, may find that certain drugs help them control their symptoms and allows them to be effective at socializing. Children, who grow up in surroundings where drugs and alcohol are openly available and misused, are more at risk to succumbing to addictive patterns of behavior.

There are a large variety of illicit substances available. Amphetamines, Ecstasy, crack and cocaine are the more commonly use stimulants. These drugs stimulate the nervous system and induce feelings of power and energy. They allow the user to keep on going for extended periods of time without sleep, but they could induce a sense of anxiety and paranoia. Exhaustion results from obvious continuous use with the possibility of long-term psychological damage. Some people believe that cocaine is a social drug with no potential for addiction, but crack and cocaine are extremely addictive. The cravings for crack are almost impossible to control; unfortunately it is these cravings that eventually lead to destructive behavior.

Other drugs have a more relaxing effect such as marijuana (cannabis), heroin and the anesthetic ketamine. Tranquilizers that are legally prescribed for short-term treatments for anxiety may also be abused as they have addictive potential. The regular consumption of marijuana may impair judgment and induce long-term psychological problems, such as demotivation and depression. Addiction has a destructive effect on relationships and employment. An addict may lose everything of value and face legal proceedings often ending up in prison.

Health risks of drug abuse are Hepatitis B, Hepatitis C, HIV, Septicemia (blood poisoning), Endocarditis (infection of the valves inside the heart), Cellulitis (infection of the skin and subcutaneous tissues) and Abscesses (especially at injection sites)

Alcoholism. Alcohol is a depressant of the central nervous system that is accepted in everyday life and most societies around the world. Alcohol taken in moderation induces relaxation and eases inhibitions. In excess, it can severely impair judgment and coordination and induce violent behavior. Regular consumption may produce physical and psychological dependence, preventing the person from working effectively. This can further lead to loss of employment and the breakdown in family relationships. The health problems associated with heavy drinking are: liver damage, vitamin deficiencies and peptic ulcers.

Compulsive Gambling. Compulsive gambling is an intense desire to gamble and the urge begins to dominate your life. It more often affects men and tendencies appear before the age of 25. These pathological gamblers continually increase the amounts of money they bet in order to experience a desired level of excitement. This kind of behavior can destroy a person's life, personal relationships, work, family and friends. In some cases, gamblers lie, cheat or even steal money, regardless of the effects it may have on anyone close to them. Therapy with encouragement from close friends and family can be successful.

Many specialists believe that there is such a thing as 'addictive personality,' which may be partly genetic. There is however, more evidence supporting that addiction is a learned behavior. One fact remains; that any form of treatment can only be effective in the long-term if the addict wants to stop and acknowledges their need for therapy.