No, estrogen does not whiten skin. In fact, research indicates the opposite.
Estrogen's Effect on Skin Pigmentation
Studies show that estrogen, rather than whitening skin, actually contributes to skin darkening. A study published in 2016 by the University of Pennsylvania (https://www.med.upenn.edu/ridkylab/assets/user-content/documents/Scientists-discover-new-pathway-for-darkening-and-lightening-skin-NewsWorks.pdf) found that estrogen increases melanin production, leading to darker skin. Conversely, progesterone has the opposite effect, lightening the skin. This effect is observed in both male and female skin cells. (https://www.pennmedicine.org/news/news-releases/2016/april/penn-medicine-study-uncovers-n)
While some anecdotal evidence suggests skin lightening in individuals on estrogen therapy (https://www.reddit.com/r/asktransgender/comments/b31dna/is_it_just_me_or_you_become_more_pale_on_estrogen/), this is likely due to other factors, and contradicts established research on estrogen's impact on melanin production. The observed effect may be due to individual variation, the interaction of estrogen with other hormones, or other unrelated changes in skin condition.
Other Hormonal Effects on Skin
It's important to note that hormones influence skin in various ways beyond just pigmentation. Estrogen can affect skin thickness and texture (https://www.reddit.com/r/asktransgender/comments/b31dna/is_it_just_me_or_you_become_more_pale_on_estrogen/), making it appear softer and thinner. However, this doesn't directly equate to skin lightening.
