Human skin is covered in hundreds of thousands of microscopic hair follicles, often called pores, that connect to oil glands located under the skin. The glands are connected to the pores via small ca- nals called follicles. A small hair grows through the follicle out of the skin. The oil glands secrete a thick oily liquid called sebum that carries dead skin cells up the hair follicles and onto the surface of the skin as well as lubricates your hair and skin to keep it soft and smooth. These oil glands (also called sebaceous glands) are primarily located on the face, back, chest, shoulders, neck, and upper arms. On our face and scalp skin we have an average of approximately 800 of these glands and follicles combined per square centimeter.
Most of the time, the sebaceous glands make the right amount of sebum. As a person approaches puberty (between the ages of ten and thirteen), the oil glands are stimulated by male hormones (an- drogens) produced by the adrenal glands of both males and females to make more sebum, and the glands often become overactive. Pores become clogged if there is too much sebum and too many dead skin cells. The secret to healthy skin is to control the oil production, not to dry out the oil completely as most treatments do. Acne (acne vulgaris) is a skin disorder that involves an inflamma- tory condition of the oil glands at the base of hair follicles. It occurs when the pores in the skin are blocked, trapping the oil, dead skin, and bacteria in the hair follicles. The blocked oil oxidizes, causing an inflammation and an influx of white blood cells and resulting in a swelling and the formation of a blackhead. Meanwhile, normally present bacteria (Propionibacterium acnes) thrive in this excess oil. Immersed in excess oil, the bacteria can rapidly increase in number. As the bacteria multiply in a clogged pore, the pore becomes inflamed and white blood cells attack the bacteria. Pus forms as the lesion enters the whitehead stage. In more severe stages, an abscess— a pus-filled pocket within the skin—may form. When you have just a few red spots, or pimples, you have a mild form of acne. Severe acne can include hundreds of pimples that can cover the face, neck, chest, and back. Or it can be bigger, solid red lumps or cysts that are painful. Despite what you may have heard, acne is not contagious, and it is not caused by dirt.
Three Main Types of Acne
Noninflammatory Acne (mild) Blackheads, also known as open comedones: These are said to be the first stage of acne. They are dilated or widened hair follicles that are filled with central, dark, solid plugs of sebum, dead cells, and bacteria, having undergone a chemical reaction resulting in the oxidation of melanin. The follicles are not completely blocked; the black appearance (can also be yellowish in color) is caused by oxidation, not dirt. You can’t wash them away. Whiteheads, also known as closed comedones: These form when skin cells and oil completely block the opening of a hair follicle. Since the air cannot reach the follicle, the material is not oxidized and remains white.
Inflammatory Acne (moderate) A blackhead or whitehead can release its contents to the surface and heal or the follicle wall can rupture and inflammatory acne can ensue. This rupture can be caused by random occurrence or by pick- ing or touching the skin. This is why it is important to leave acne prone skin relatively untouched. Papules: This small, rough textured bump is a type of whitehead (5 mm or less) that occurs when the wall of a hair follicle breaks and caves in due to inflammation and infection. White blood cells rush in, and the pore becomes swollen, red, and has pus at the top. Pustules: This whitehead is pus-filled and inflamed (the white blood cells have risen to the surface of the skin). Once they rupture into the skin, they form pustular heads and are what people usually refer to as a “zit” or “pimple.”
Cystic Acne (severe) A papule or pustule can completely collapse or explode, severely inflaming the surrounding skin and may engulf neighboring fol- licles. These lesions are called cysts or nodules. Cysts: These sac-like lesions contain a buildup of white blood cells, bacteria, and dead cells in a liquid or semi-liquid state (boil-like infections). They can result in scarring and may be very painful and severely inflamed. Cysts and nodules often appear together to form nodulocystic acne, also very severe.
Nodules: Sometimes the bottom of a follicle will break off, which causes the follicle to completely collapse. This produces large solid, dome- or irregularly shaped, pus-filled lesions/lumps that extend deep into the skin, sometimes causing tissue damage and scarring if not treated. Nodular acne, which can be painful, is the most severe form of the disease.