Is Skin Whitening Prohibited in Islam?
Question

In some parts of my body (mainly private parts) the skin color is very darker compared to the main skin color of my body, is it permissible to change it so it is the same as my normal skin color by bleaching or by other methods? Please note it was not like this before.
Praise be to Allah.Is skin whitening prohibited in Islam?
There is nothing wrong with changing the colour of the skin from dark to white, using creams, cosmetic preparations and the like, if the change is temporary. But if it is changing the colour of the skin permanently, then it is not permissible, whether that is done by means of surgical procedures or other means, because that is changing the creation of Allah, may He be Exalted.
Shaykh Ibn `Uthaymin (may Allah have mercy on him) was asked: What is the ruling on whitening creams for the skin? Is there anything wrong with using them for women?
He (may Allah have mercy on him) replied: 
“If the whitening is permanent , then it is not permissible, because this is akin to tattooing and filing the teeth . But if it is whitening the face for a specific length of time, and when it is washed it will disappear, then there is nothing wrong with it.” (Fatawa Nur `Ala Ad-Darb)
He was also asked: Recently there has appeared medicine that makes a dark-skinned woman white; can she take it or is taking such medicine prohibited because it is regarded as changing the creation?
He (may Allah have mercy on him) replied: 
“Yes, it is prohibited if it changes the colour of the skin permanently. In that case it is like tattooing, and the Prophet (blessings and peace of Allah be upon him) cursed the woman who does tattoos and the woman who has tattoos done. But if it is done to remove a defect, such as if there is a dark, disfiguring mole on the skin and the individual uses something to remove it, then there is nothing wrong with that.” (Fatawa Nur `Ala Ad-Darb)
Using medicines to restore the skin to its original colour
If the skin was originally white then it turned darker for some reason or because of sickness and the like, then there is nothing wrong with using permissible creams and medicines to restore the skin to its original colour. This is not regarded as changing the creation of Allah , because it is removal of a defect that has occurred and is not changing the original form.
But we should point out that a man should not be preoccupied with such matters or go to extremes in paying attention to them, because it is a waste of time and money on something that does not bring much benefit, and it may distract him from things that are more important and more beneficial. It is not befitting for men to be preoccupied with adornments and beautification; rather they should be focused on more important matters.
Have you not heard what the poet said:
War and fighting have been decreed for us and for young women it is decreed that they should wear beautiful garments.
And Allah knows best.