As different drugs have different effects, can be used for different reasons. In agreement with the hypothesis of the Self-medication (SMH), the election of the individuals of a medicine in individual is not accidental or accidental, but that, as resulting from the condition of the psychological individuals, as the election drug provides a lightening for the user of its individual characteristics or their condition. In particular, the addiction is the hypothesis that compensatory works like means to modulate the affection and the treatment of psychological states that afflict, allows the participants to choose the medicine that more appropriately to handle its specific type of psychiatric anguish and to help them to obtain the emotional stability.

The hypothesis of the Self-medication (SMH) was originated in the papers of Edward Khantzian, Mack and Schatzberg, David F. Duncan, and an answer to Khantzian by Duncan. The SMH was centered initially in the heroin consumption, but a document of added pursuit SMH cocaine. The later was extended to include the alcohol, [8] and, finally, all drugs of addiction.

In opinion of Khantzian of the addiction, the drug users to compensate deficient function of I by means of use of a drug like “a reliable” ego, that acts on the parts of the car which they cut themselves of the conscience by defense mechanisms. According to Khantzian, the dependent individuals of drugs in general experience anguish with more psychiatric than they do not consume drugs dependent people, and the development of the drug dependency implies the gradual incorporation of the drug effects and the necessity to maintain these effects in the defensive activity structure of the construction of I itself. The election of the addict one to drugs is the result of the interaction between the affective properties psychogenic of the drug and states of which the addict one looks for lightening. The drug of effects of substitution of the mechanisms of the defective or nonexistent ego of the defense. The addict one to election drugs, therefore, is not random.