Rinse your hands immediately under cool running water.
Scrub your hands with cool water and a slightly acidic or a pH-neutral cleanser. If you are unsure of the pH value of your cleanser, do not use it.
Bathe your hands in a solution of vinegar and water if you do not have a pH-neutral cleanser. Use about half vinegar and half water. The mild acidity will help to neutralize the grout's caustic properties.
Dry your hands gently. If you have any open cuts, sores or otherwise damaged skin on your hands, cover the cuts with a bandage.
Go to the hospital as soon as possible if you have cuts on your hands or if you notice irritation, burn marks or other damage to your skin.