Estrogen is a female hormone produced in the ovaries. There are estrogen receptors all over the body, including the skin. Estrogen is responsible for growth tissue stimulation, such as breast development during puberty. In the brain, it boosts the synthesis and function of neurotransmitters that affect sleep, mood, memory, libido, and cognitive factors such as learning and attention span.
 

Estrogen decreases the perception of pain, preserves bone mass, and increases HDL – the good cholesterol. It also maintains the elasticity and moisture content of the skin, dilates blood vessels, and prevents plaque formation in blood vessel walls.
 

When estrogen levels are deficient, acne may develop. Generally speaking, when estrogen levels go down, testosterone levels go up. There can also be other influences on hormones so keep in mind this is a generalization. 
 

We see this most often with clients who are on “Lo-dose” (low estrogen) birth control pills or devices such as an IUD or implant. The estrogen drops so low that the period can even stop, and the elevated testosterone triggers acne breakouts to develop. This process is called the "teeter-totter" effect....as the estrogen goes down, the testosterone goes up. 
 

Keep in mind, this does not mean that testosterone is "high" in the sense of a hormone lab test. On a lab test, one may still be in the "normal" range. Most people think that having hormonal acne means elevated testosterone in a medical test, but this is not typical. Instead, what is happening is that acne-prone individuals are just more sensitive to the effects of testosterone.