Why does acne appear most often in teenagers?

The main trigger of acne is extra hormones — specifically, testosterone, often referred to as the “male hormone,” (However, Women have testosterone too.) When teenagers hit puberty, their hormones start surging — and then, the acne acts up. However, acne is not just in teenagers. 

• 51% of women 20 -29 years old, 
• 35% of women 30-39 years old, 
• 26% of women 40-49 y/o 

have acne per a study in 2008.