More than half the younger population in Denmark have tried water-pipe smoking, but very few smoke daily or weekly. Water-pipe smoke contains approximately the same harmful substances as cigarette smoke. Accordingly, it is expected that water-pipe smoking will have the same harmful effect on health and be as addictive as other forms of tobacco smoking. The limited epidemiologic evidence seems to indicate that water-pipe smoking is as damaging to health as other forms of tobacco smoking. A Cochrane-review did not find a single study of water-pipe smoking cessation.