Certain parts of the body normally tend to be darker than other parts; this is no indication of any kind of health problem, and is nothing to be worried about or ashamed of. For most people, areas such as the genitals, the whole groin area, the arm pits, and the buttocks are darker than the rest of the body. As you mentioned, this is partly due to the constant friction that these parts are exposed to, which causes the skin to become dark over time. In addition, pimples and boils often leave behind dark spots of skin; this is known as post inflammatory hyperpigmentation, and is a common occurrence. The good news is that this darkening does not last for a very long time - in most cases, it should fade within a couple of months, after which the skin returns to its normal color. However, even apart from these factors, this skin tends to be dark and uneven, so you should not expect any treatment to give your skin a completely even tone.
That said, you can try some of the following home remedies, and over time they should help the skin to become lighter in color. One treatment for your darkened skin is cocoa butter, which is also used for several other problems with skin color and texture. You can apply this about an hour before you bathe - leave it on your skin for an hour, and then wash it off normally. After bathing, and in fact several times a day, you should also apply aloe gel to the affected areas. Aloe is good for most skin problems, particularly if you can get fresh aloe gel from a plant; even if you can't, commercially sold aloe gel is good enough, as long as it is not mixed with any other substances. Vitamin E is another substance that is excellent for the skin. It is often added to many creams and other skin products, but is also available in the form of an oil, and this is the best way to use it. You can apply a little bit of this oil daily, before going to bed.
Another excellent home remedy for most skin pigmentation problems is a mixture of sandalwood powder and turmeric powder in a tablespoon of honey. You can apply this once a day, leave it on for half an hour, and then wash it off with plain water.
answered by G M