If you wash your hands a lot, you should moisturize your hands a lot. The more you wash, the more moisture is stripped out of your hands, leaving skin dry, rough, patched and broken. This is especially prevalent during cold, dry weather, when your skin has enough trouble retaining moisture as it is. Moisturizing with the right type of product and the right frequency keeps skin healthy and protected.
When you wash your hands frequently, you also have to do it wisely. Careless scrubbing can do some serious damage to your hands, as far as moisture goes. For example, don't use hot water to wash your hands -- it dries out skin and robs you of beneficial natural oils. Use warm water, instead. Use moisturizing soaps or even cleansers that aren't labeled as "soap," as soap dries out the skin, too. Gentle, fragrance-free cleansers are easier on your skin and less likely to sap it of its moisture.
Oil, Not Water
The best moisturizers for a frequent hand-washer are heavy on oil and light on water. Lotion, for example, is high in water, while ointments are higher in oil. In fact, Harvard Medical School recommends applying plain oil products like baby oil to skin while it's moist, like immediately after washing your hands. Alternatively, petroleum jelly gives you the same benefits -- while it may feel a bit goopy sitting on the surface of your skin, it locks in moisture and protects your hands after they've been washed and gently patted dry.
If your hands are already severely dried and cracked, over-the-counter ointments and creams may not cut it. Consult with a dermatologist, because seriously damaged skin can be prone to infections, and it needs prescription-strength care. It's very likely that the product she prescribes won't be lotion at all but rather a steroidal cream or ointment with a higher concentration of active ingredients like hyaluronic acid.
Whether you're using lotion or another product to moisturize your dry hands, you have to do it frequently. Apply it generously at least five or six times a day, and always immediately after you wash and dry your hands. This is particularly important if you are, in fact, using lotion, because according to the National Eczema Association, it is less beneficial than creams and ointments.