A large variety of local anaesthetics is widely used in dental clinic. Cautious application is essential in order to avoid adverse events of potentially lethal nature. The objective of this article is to present an overview of the mechanisms and to underline potentially lethal adverse effects and contraindications. The knowledge of specific side effects is vital in daily practice. An overview on specific products is accessible on www.kompendium.ch, however users have to be aware of the fact that this source may be incomplete.