Acne is a skin condition commonly found in adolescents from any time between the onset of puberty and the mid-twenties.
It is less often found in those in their 30s and 40s.
It can be a very traumatic experience for those who suffer with it, causing a significant amount of emotional distress.
Acne is caused by glands in the skin which normally act to keep the skin supple.
They release oil which prevents the surface of the skin from becoming too dry, but in those people who suffer with acne these glands produce too much oil.
Thus one feature which usually characterizes acne is overly oily skin.
Other features which are very common to acne sufferers are blackheads, whiteheads, red or yellow spots and scarring.
The scarring usually results from the larger spots having been damaged and not healing properly.
In some cases this cannot be avoided, though picking spots will make the scarring far worse.
Owing to the excess oil produced by the sebaceous glands in the skin, dead skin cells fail to shed properly.
They clog up hair follicles which results in the formation of whiteheads and blackheads.
Maintaining clean skin is important to help reduce this effect, but it is also important not to use excessive amounts of soap as it dries out the skin.
The redness which commonly accompanies acne is also caused by the excess build-up of oils and dead skin cells in the hair follicles.
This allows a bacterium that normally resides in the skin harmlessly to multiply more than usual which triggers an immune response creating redness in the skin.
In worse cases the bacteria can cause cysts to develop beneath the skin, resulting in painful areas and worsening scarring.
The reason that acne is so common amongst adolescents is that the hormone testosterone promotes the sebaceous gland's excess oil production.
Testosterone levels are usually at their highest during this age-range which results in an increased susceptibility to acne during the years of puberty and early adulthood.
Acne is worsened by picking as it spreads the bacterial infection into nearby skin.
Therefore, although picking may seem to alleviate a spot's immediate presence, the result will be to worsen the situation in the future.
Stress can also worsen acne, as can excessive testosterone levels.
Some medicines can have a negative effect on the skin condition too.
A popular belief is that eating greasy or sugary foods makes acne worse.
However, the medical evidence does not show a link between the two, so doctors will tell you not to worry about what you are eating.
The medical stance is that this is due to other factors besides the food and that any apparent connection is only coincidental.
Whilst there are underlying causes of acne, it occurs in a number of people and can sometimes start in late twenties without any earlier skin problems.
Nevertheless, a number of treatments are available which can help to avoid the condition by keeping the skin free from bacteria.