Hi M.,
I've read the responses you've received thus far, and many of them are right on the money. Before moving to California I worked for dermatologists and plastic surgeons in Manhattan, NY.
First you should ask your self a few questions:
Where are the dark patches and how severe are they?
How sensitive is your skin? To products, sun, stimulation, etc...
What is your family history regarding the skin issue/s you are concerned with? Genetics play a major part.
What is your medical history? Is there something that caused the “spots/patches” to appear? Age, diet, environmental (excessive sun exposure), and physical (birth of a child) all need to be considered before you select a product or regimen.
How compliant will you be using your choice of skin care? And are your expectations realistic?
How aggressive are you willing to be with you choice of treatment?
Is an organic, homemade, or over-the-counter product something you might choose? (Please note, most products sold over the counter - i.e. in a drug store or the like, are not regulated/managed by a skin care professional or MD thus they cannot by mandate of the FDA have the same amounts of active (aggressive) ingredients in them due to the chance of over use and or harm to the consumer.) With-that-said medical grade skin care isn't necessarily better. It simply, in most cases, works faster and you have a skin care professional overseeing your progress and care. Many products are know as “systemic”, they not only affect the area/s to which they are applied, they can affect/change other areas as well. This is especially true when using many medical grade products. Areas to avoid are - eye area, nostril area and around the lips. These areas are VERY sensitive and react to products even if they have not been applied to them. This is not to say you should not consider medical grade products, on the contrary, it is simply a word of caution. Nothing is worse than feeling bad about an aspect of your appearance and unknowingly causing another area of concern.
M., these question can only be answered by you.
I can suggest what many of the other women have already suggested 2% Hydroquinone. You MUST wear sunscreen while using this product. You will experience red skin in the area you have applied the cream/lotion. Once your skin adjusts you will notice the areas fading. I am not and do not represent the following product suggestion, I know it works because it worked for me and for many of the clients who came into the offices I worked for in Manhattan. If you should be interested, try the Glytone products. They are corrective yet not too aggressive. There are other more aggressive products like Obagi, and less aggressive products like Dermalogica. Whichever you choose keep in mind, skin cells take 6 weeks for complete turnover. Although you may notice change before then, you should give any product 6 weeks before you go on to the next one.
I wish you only the very best.