Oil Glands & Hormones

Sebaceous (oil) glands are located deep in the skin.   Each oil gland is connected to a tiny canal (follicle) that contains a hair.  The sebaceous oil flows to the surface (pore) of the skin through the follicles to lubricate the follicle and surrounding skin.

Sebaceous glands are found over most of the body, although there are few on the hands or feet and none on the palms and soles. Sebaceous glands on the mid-back, forehead and chin are larger and more numerous than elsewhere (up to 400-900 glands per square centimeter).

Sebaceous glands, which vary in size, are stimulated to produce oil by hormones, specifically hormones called androgens. These hormones are produced by the testes in men and by the ovaries in women.  In both sexes, androgens are also produced by the adrenal glands. During puberty, the oil glands become overactive in response to hormonal changes, and during times of stress, the adrenal glands produce increased levels of hormones, causing enlargement of the oil glands. 

Sebum is a complex and variable mixture of lipids including:

• Glycerides
• Free fatty acids
• Wax esters
• Squalene
• Cholesterol esters
• Cholesterol

Sebum has the following functions:

• It reduces water loss from the skin surface
• It protects the skin from infection by bacteria and fungi
• It contributes to body odor
• It is colonized by the bacteria Priopionibacterium acnes, which may have a role in immune regulation

Sebum production vares with age.  Sebaceous glands are already active before birth. They are regulated by the mothers hormones and those made by the fetus itself.  The composition of oils on the skin surface varies with age:

• The fetus produces vernix caseosa, a waxy protective layer
• For 3 to 6 months, sebum produced by a newborn baby resembles that of an adult
• Thereafter until the age of 8 it has less wax and squalene and more cholesterol
• Sebum production increases at puberty up to fivefold in men
• Adult males produce slightly more sebum than adult females
• Sebum production declines with age, particularly after menopause in females

Most individuals develop acne during their adolescence when hormonal changes create elevated sebaceous oil production.  The more sebum produced, the more likely it is that follicles will become blocked and acne will occur.

• There are higher level of sex hormones at puberty than in younger children.  
• These hormones are converted in the skin to dihydrotestosterone (DHT) which stimulates oil glands to enlarge.
• The oil glands, called sebaceous glands, produce sebum. The more sebum, the more likely it is that acne will become troublesome.
• If sebum and keratin (dead skin cells) block the skin pores, comedones (acne whiteheads) can develop.
• The wall of the follicles may rupture.  Bacteria and comedonal debris cause acne pimples or pustules (inflammatory lesions).

Acne typically becomes less prevalent after age 25 when the most dramatic hormonal changes have already occurred.  About 15% of women and 5% of men continue to suffer with adult acne.

Some individuals may have naturally or environmentally elevated hormonal and sebaceous oil levels causing severe and persistent acne.

• Genetic factors.  The family may have skin that is naturally more oily than normal.
• Indirect Hormonal issues.  Indirect factors can cause elevated hormonal and sebum) levels.
• Polycystic ovaries (common)
• Psychological stress and depression (somewhat common)
• Excessive corticosteroids - Cushing's disease (rare)
• Pituitary, adrenal, ovarian or testicular disorders may increase or the amount of sebum.  Parkinson's disease increases the amount of sebum (rare)
• Enzyme deficiency - sterol hydroxylase deficiency (very rare)
• Environmental factors such as the following can cause elevated oil production.
• High humidity
• Cosmetics especially certain moisturizers, foundation and pomades (watch out for lanolin, petrolatum, vegetable oils, buty stearate, lauryl alcohol and oleic acie)
• Petroleum oils
• Pressure from headbands & chin straps (eg: "fiddler's neck")
• Medications.  Certain hormonal medications that are androgenic in nature may aggravate acne by increasing oil production and pore blockage. Examples include anabolic steroids, and a component of birth control pills called progestin. Other commonly used medications that may aggravate acne include lithium, and some anti-seizure medications.