Is dandelion a diuretic

Absolutely, it is! I would refer you to Materia Medica's page where you can read about dandelion's diuretic qualities. In fact, if you are able to take 1/2 to 4 oz of dandelion leaf infused in from one pint to 3 liters of water each day, it can be about equivalent to taking furosemide, a prescribed chemical diuretic, but without the potassium loss, because dandelion leaves actually contain enough potassium to replace that potassium being lost by diuresis.