Small children, older than one year of age, can bear as many drugs as mature people can. They can bear some drugs even better than older people, but show unusual sensitivity towards certain drugs. The occurrense of dose-dependent adverse drug effects can be influenced by pharmacokinetics (limited biotransformation-inactivation and elimination of drugs). Only a few drugs can cause adverse effects occurring almost exclusively in children. Even if rare, pediatric adverse drug reactions may be life-treatening. It should be pointed out that many drugs are restricted for children, and many drugs, in spite of the fact that are in clinical practice for several decades, contain no approval for use in children.