Globally,<unk>  affects approximately 650 million people, or about 9.4% of the population, as of 2010. It affects nearly 90% of people in Western societies during their teenage years, but can occur before adolescence and may persist into adulthood. While<unk>  that first develops between the ages of 21 and 25 is uncommon, it affects 54% of women and 40% of men older than 25 years of age and has a lifetime prevalence of 85%. About 20% of those affected have moderate or severe cases. It is slightly more common in females than males (9.8% versus 9.0%). In those over 40 years old, 1% of males and 5% of females still have problems. Rates appear to be lower in rural societies. While some research has found it affects people of all ethnic groups,<unk>  may not occur in the non-Westernized peoples of Papua New Guinea and Paraguay.<unk>  affects 40–50 million people in the United States (16%) and approximately 3–5 million in Australia (23%). Severe<unk>  tends to be more common in people of Caucasian or Amerindian descent than in people of African descent.
Acne
Hidradenitis suppurativa
Oscar 
Miliaria
Sunburn
Rosacea
Scar
Folliculitis