When hair follicles on the skin secret a natural oil called sebum, this old travels to the pores of the skin to protect and lubricate. Some people have skin disorders where there is excess secretion of this natural oil. This phenomenon is also common among young people entering puberty where hormonal changes take place.

Excess sebum can clog the pores of the skin. Since this is a sticky substance, this could attract bacteria that touch the skin and form spots and inflammations that develop into acne.

The forms of actually are inflammatory and non-inflammatory. The smallest form which is also the start of acne is called microcomedo. This may develop into either blackhead or whitehead. Pustules and Nodules are similar to comedo but more serious. Pustules have pus-filled bumps and yellowish color. Nodules are inflammations under the skin and have larger size and firmer than the Pustules.

Papules are another form of acne that comes between inflammatory and non-inflammatory. They are the typical pimples which are mildly inflamed and do now show redness or contain pus. Acne Vulgaris is the most common type of acne and is composed of both blackheads and whiteheads. This is not very serious though can be easily treated with both over the counter and prescription medications.

Pinching or squeezing of small pus-filled acne could lead to cystic acne. This can result to pain brought about by deep rooted inflammation.

Acne Rosacea is common among middle aged adults. This type of acne is makes the nose red due to inflamed bumps. Most common infected areas are the chin and forehead. The face can also looked flushed giving the affected person an impression of being drunk. When in severe stage, Acne Rosacea can cause bulbous nose (rhinofima).

Some women get affected with perioral dermatitis wherein small pustules and papules form on the chin, around the mouth and sometimes near the forehead and eyelids. The cause for this may be attributed to fluorinated toothpaste and steroids, which is also the cause of corticosteroid acne.

Even babies are not spared from acne. Although rare, infantile acne can be present on new born babies. This is no reason to worry though because this kind of acne is very mild and may disappear after a few weeks. This may be caused by fetal hormones.

There is also a type of acne that develops in the scalp and is called scalp folliculitis. Lack of hygienic practice in the scalp area and oily type of hair can accumulate bacteria to form acne. This type of acne can be treated with acne-fighting shampoos.

Acne conglobata is a severe form of nodular cystic acne vulgaris that extensively affects the face, chest and back. Multiple inflamed and non-inflamed nodules and scars are found in many parts of the body. A severe form of acne conglobata is the very rare Acne fulminan. This is very common among men.