It's a medicated shampoo though, so is quite potent - I certainly wouldn't use anything that strong if the piggy was healthy as everything leaves a residue they will then ingest, and if they're healthy it's completely unnecessary (and this is regardless of my opinions on using human shampoos on small animals).
Shampoos made for small animals are made with their grooming behaviour in mind, and you should always use as mild an animal shampoo as you can unless your vet suggests a skin condition would benefit from a medicated shampoo. Guinea pigs shouldn't need to be bathed more than a couple of times a year (if that) and it's best not to interfere with the balance of natural oils in their coat any more than is necessary.