Skin blemishes are a nuisance in adolescence but for some people they occur in adult life as well. Unfortunately, adult cases of acne are often more persistent than teenage acne, and this can be particularly frustrating for those who were spared outbreaks as teenagers.

Nearly 103 million people worldwide suffer from blemishes making them the most common skin problem. Clinique recently conducted a Global Truth in Beauty Survey in which almost 10,000 women from 12 countries were asked questions about their beauty habits and perceptions.

Women in China, Japan and South Korea claim that blemishes are their biggest skin care challenge - ahead of age spots, lines and wrinkles.

They also place more importance on beautiful skin than beautiful facial features and feel that having beautiful skin is possible if they take good care of themselves and their skin.

According to Dermalogica, the primary catalyst of adult acne is chronic stress.

Balancing personal and professional responsibilities makes this generation of adults the most time-compressed generation in history, contributing to chronic stress: the constant, continued and heightened level of stress that throws our adrenal glands into overdrive, which in turn can boost sebum production, setting the stage for acne development.

While stress can trigger acne, there are four main factors that contribute to the development of acne: overactive sebaceous glands (the production of too much oil), dead skin cell accumulation, bacteria and inflammation.

"Blemishes start when the sebaceous glands produce too much oil," says Tom Mammone, executive director of Clinique Research and Development.

Sebaceous glands attach to the skin's hair follicles like little sponges.