An example of a thiazide diuretic?

Diuretics are substances that make you pee more, they make your body lose water.

Beverages containing alcohol and caffeine are sort of accidental diuretics - that is, they're not drunk with the purpose of losing water but it happens anyway.

Then there are substance that are taken with the explicit purpose of losing water.

Sometimes in accordance with doctor's recommendations, as there are diseases that make the body hold on to too much water.

Sometimes by own initiative, in order to quickly lose a bit of weight, or to get more muscle definition.

Accidental use often isn't much to worry about, but self-medication should be avoided.