My wide has a cat allergy, but loves cats. We've never heard of a cure you give to the cat, but she has considerably alleviated her symptoms by:
Daily, thorough vacuuming throughout the house.
Keeping the cats out of the bedrooms and only having them in the living room in the evening.
Regular, hot washing of sheets & duvet covers. Vacuuming pillows. Airing duvey weekly.
Occasional vacuuming of curtains.
Although our cats won't stand for it, washing the cat regularly (good wash monthly, 'wipe down' weekly) is said to help immensely.