AStrong evidence, for the people named belowOther
The short answer
One of the very few sports supplements with evidence that holds up. Cheap, well studied, and does nothing for anyone who is not training.
Who this is actually for
People doing resistance or repeated high-intensity training who want a measurable gain in strength and power output.
What it is legally allowed to claim
Nothing. There is no authorised EU health claim for this substance, so any packet promising a specific benefit is making a claim it is not entitled to make. That is worth knowing before you judge the price.
How much is too much
No EFSA upper level. Three to five grams daily is the studied maintenance dose.
Cautions and interactions
Safe in healthy people over long study periods. Expect one to two kilograms of water weight. If you have kidney disease, ask first.
Ask a pharmacist before you start anything. Interactions with prescribed medicines are the most common way supplements cause harm, and they are easy to check. Bring the actual packet, or a photo of the ingredients panel, because doses and forms vary enormously between products. Nothing here is a substitute for advice about your own situation.