Itch induced by water contact is called Aquagenic Pruritus. It is pretty rare and it is a type of neuropathy…Beta Alanine is an amino acid that occurs naturally in the body…you can supplement with an otc beta alanine…I take 750 mg to kill random itch, and 1500 mg 30 mins before water exposure/showering…for some reason, it works best later in the day…
Beta Alanine is typically used as a preworkout supplement and at higher doses can cause tingling on the skin.
I buy the NOW Brand from Amazon, 750 mg capsules…it kills the itch…