This book provides a didactic presentation of current scientific knowledge on the characteristics and effects of cannabis. Every aspect of the substance is thoroughly examined here, from its chemical makeup to its effects on the mind, the emotions and behaviour.
The author aims to refute the argument that cannabis is less harmful than tobacco or alcohol, and that its consumption should therefore be tolerated.
He does not, however, seek to demonise cannabis out of moral or puritanical considerations. Instead, he cautions against the increasingly toxic cannabis that is now in circulation and against its especially harmful effects.
This book is a warning. The author argues that smoking is not innocuous — particularly during adolescence, when the brain’s development is being completed and our mental and psychological framework is still establishing itself.
He urges parents to remain vigilant and to convince teenagers of the dangers of cannabis.

Jean Costentin directs a research unit in neuro-psychoparmacology, associated with the Centre National de la Recherche Scientifique (CNRS). He is a member of the French National Academy of Pharmacy and the author of Les Médicaments du cerveau (1993).