Unless it is specifically an alcohol-free gripe water they do contain approximately 4% alcohol by volume. It's like giving babies a teaspoon of weak beer

but the herbs found in gripe water are wonderful, and if you can get an alcohol-free one it would help.
But my doctor said never to worry about hiccoughs. they're seriously scary looking sometimes (Zed's whole torso would deform and it looked like his ribs were bending inwards) , but they bother you more than your baby.