The outermost layer of your skin, the stratum corneum, is composed of dead skin cells and oils that help keep your skin moisturized. This layer of skin helps retain water, which keeps the living skin beneath it healthy and moisturized. If the stratum corneum breaks down and is unable to retain this water, the result is dry skin [source: University of Iowa].
You may enjoy long, hot showers and the smell of your soap as you lather up, but this habit could be drying out your skin. Hot water and certain soaps, including scented, deodorant and antibacterial soaps, can remove natural oils from your skin and allow moisture to escape [source: Fries]. Low humidity levels, which are often caused by cold, dry weather or arid climates, or your home environment -- with the furnace or air conditioner circulating dry air -- could also be the culprits [source: Mayo Clinic].
You may think using a moisturizer will solve your dry skin problems, but if you use the wrong lotion or apply it incorrectly, you could be doing more harm than good. Avoid scented lotions -- opt for moisturizers that are gentle and contain humectants and emollients. Humectants attract water from the air and retain it in your skin, and emollients act as lubricants and smooth the skin [source: Kraft].
Sometimes medications can also cause dry skin -- if you're taking allergy, acne or blood pressure medications, they could be the source of your itchy, flaky skin. Medical conditions, such as psoriasis and eczema, can also sap your skin of moisture, and they tend to cause dry patches on the body [source: Griffin]. Keep reading to learn more about these dry patches.