Acne usually commences in early adolescence, and usually resolves in the early 20s, although it can last longer. It may affect around 80% of people during their teenage or early adult years.
Factors that can cause unhealthy or unsightly nails include poor hygiene, infections, trauma, underlying health problems, and poor nutritional status.
Stretch marks on the skin are more common in women than men, and vary in size and shape.
Dandruff is very common, and is simply the sloughing off of skin cells from the scalp in scaly clusters.
Psoriasis is a chronic condition characterised by red, scaly plaques on the skin, which may or may not be itchy.