What is Acne?
Acne affects most of us at some time in our life. It affects over 85% of adolescents and young adults and it is the most common skin disease treated by physicians. Acne is a chronic condition, meaning that dealing with it can become an ongoing process involving lifestyle and nutritional changes as well as a skin care routine. Everyone is different, and the treatments you opt for will depend upon a many individual factors. One of the first steps towards clearer skin, however, is understanding what type of acne you suffer from.

Types of Acne
Not all acne is the same and different types of acne require different treatment. At a basic level, acne can be divided into red bumps and blackheads/whiteheads. Blackheads and whiteheads, known as comedones, tend to be more numerous than red bumps filled with pus, especially on the face and shoulders. An effective daily skin care routine is key to treating this type of acne.

Why Does Acne Occur?
Essentially, acne occurs when normal healthy skin functions are disrupted. All acne is a disorder of the pilosebaceous unit, which is made up of a hair follicle, sebaceous gland, and a hair (fig A).

These units are found everywhere on the body except the palms, soles, top of the feet, and the lower lip. The number of pilosebaceous units is greatest on the face, upper neck, and chest. Sebaceous glands produce a substance called sebum, which is responsible for keeping the skin and hair moisturized.

Sebum production is affected by hormonal changes in the body and generally after the age of about 20, sebum production decreases.

Sebum production is essential to skin health. It maintains skin moisture and helps to protect the skin against environmental stress and infection. Herein lies the paradox – many acne treatment regimes involve stripping away sebum. Although, as we shall see below, preventing and removing sebum blockages is a necessary part of acne treatment, leaving the skin stripped of its protective layer can leave it stressed and prone to reinfection.

So, although sebum is essential to skin health, problems arise when natural sebum processes are disrupted. This occurs when some hair follicles become obstructed, preventing sebum from flowing normally.

When this happens, a certain bacteria called Propionibacterium acnes multiplies in the trapped sebum and causes a tiny infection. The presence of bacteria attracts white blood cells to the follicle. These white blood cells produce an enzyme that damages the wall of the follicle, allowing the contents of the follicle to enter the surrounding skin tissue. This process causes an inflammatory response. The bacteria also cause the formation of free fatty acids, which are irritants, increasing the inflammatory process in the follicle. This leads to inflammatory acne, or red bumps and pustules.

In some follicles the bacteria does not cause an infection, but rather changes the lining of the hair follicle and forms plugs called comedones. There are two types of comedones:

Blackheads

Blackheads, also known as open comedones, are follicles that have a wider than normal opening. They are filled with plugs of sebum and sloughed off cells and have undergone a chemical reaction resulting in the oxidation of melanin. This gives the material in the follicle the typical black color.

Whiteheads
Whiteheads, also known as closed comedones, are follicles that are filled with the same material, but have only a microscopic opening to the skin surface. Since the air cannot reach the follicle, the material is not oxidized, and remains white.