I use German Chamomile essential oil. Only one drop is needed for a big patch of eczema. Try to get a good brand of oil, (Young Living is the best although it's pricey), Simplers you can get at the health food store. It has plant enzymes that make the itch-irritant substance neutral.
Even better, put them on a cleansing diet so their body stops producing anti bodies to something that is irritating them. Try to eliminate what it is they are allergic to, highly possible it is a food.