I want to know if it is possible that PCOS can cause women to have darker vagina's?
It depends on what you mean by darken and where specifically.
The vagina is the actual birth canal/opening. The vulva is the external genitalia. Is that where it's darkening?
If so, dark patches are most typically caused by acanthosis nigiricans, which is not really a PCOS issue, but really an insulin issue.
It just happens that a lot of PCOS women have insulin resistance.
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Acanthosis nigricans (AN) is caused by insulin resistance or diabetes and results in darkening of the skin in the armpits, below the breasts, on the back of the neck, and in the groin area.
Your body doesn't use the insulin properly, so your panceas keeps producing more and eventually it affects the skin by causing discoloration and sometimes thickened ridges.
Mine improved drastically back in 2002 when I went on a strict low carb diet, exercised 30 minutes a day, and lost 30 pounds in three months. Metformin or other diabetes medications can help as it helps your body to use the insulin more efficiently and your pancreas not to make so much.
Creams and topical treatments can't really help because it's an internal problem that needs to be treated internally. Until you address the cause, it will never go away.
Other cysters have lost their excess weight and gotten their sugars balanced out and have had it disappear completely as a result.
I've been taking Metformin for over a year now and the dark skin on the back and sides of my neck has pretty much disappeared. It did look just like the picture below. The skin still feels a bit textured though.
In my groin area, in the crease of my legs, and on my inner thighs, it almost looks like someone slapped tan paint on me. It's embarrassing and I hate going to the gyno because of it. I don't really have the thickened skin down there, though.
Here are some pics of it on the neck and armpits, if people want to get an idea what it looks like:
I'm like 180 pounds and I'm dying to lose weight. I also want to get my stomach flat, I have the dreadful apple shape
I was referring to the labia majora being so dark!
Darken of vagina from PCOS 
thank you for the reply. 
