Does alcohol-free beer give you a hangover?

Not from the alcohol - at 0.05% ABV or below there simply is not enough alcohol present to cause the dehydration, disrupted sleep and toxic byproduct build-up (like acetaldehyde) that drive a classic hangover.

That said, some people report feeling a bit rough after drinking a lot of alcohol-free beer in one sitting - usually down to the carbonation, sugar content, or simply drinking a large volume of fizzy liquid, rather than anything alcohol-related. It is closer to overdoing it on soft drinks than a real hangover.

If you are drinking alcohol-free beer specifically to avoid hangovers after a heavy session the night before, it will not undo alcohol you drank earlier - it just will not add to the problem.