As I mentioned in an earlier post, I was recently asked to find a natural product to help lessen the appearance of age spots. Age spots, officially known as lentigo, are uneven melanin deposits in the surface of the skin. These can occur for a variety of reasons such as a greater amount of melanin produced in a certain area of the skin, melanin not being properly absorbed by the kerantinic cells, hormonal imbalances, or even irritation of the skin including those caused by acne conditions.
If you are using a commercial bleaching agent (and even some natural ones like lemon juice) to lighten age spots, avoid applying the product before going into the sun. Many of the ingredients used to lighten the skin can react with the sunlight, making the problem worse. In fact, anytime you are out in the day, be sure to use sunscreen. If you do not, not only do you risk creating new age spots but you may be negating any effect the bleaching product you are already using may be doing.
Some of this information came from Milady's Skin Care & Cosmetic Ingredients Dictionary. Be sure to check it out if you would like more information.