It depends on the shisha. A lot of the shisha varieties you find within the West have little to no nicotine in them, but in places like Egypt the shisha is very, very strong tobacco that will have your head swimming after a few good puffs. However, even shisha with almost no nicotine in them (these tend to be the fruitier, better tasting ones) are still horrible for your lungs, because it's the smoke itself which creates problems for your lungs, not the nicotine.