Sebum is an oily substance produced in the sebaceous glands. It mixes with fat molecules, called lipids, to form a protective coating on the skin’s surface.
These lipids help hydrate the skin and protect it from potentially harmful pathogens, such as bacteria and fungi.
In this article, we explore how sebum is produced and what to do if the skin has too much or too little.
Sebum is a sticky, oily substance produced by the sebaceous glands, which sit in the middle layers of the skin, near hair follicles.
Sebum helps moisturize and protect the skin.
It contains several types of fat molecule, or lipids. Human sebum consists of 57.5% triglycerides and fatty acids, 26% wax esters, and 12% squalene, a lipid.
The face, scalp, and chest have the highest concentrations of sebaceous glands — each area of skin may have up to 900 of these glands per square centimeter.
The sebaceous glands produce sebum through holocrine secretion, a process of programmed cell death. Specialized cells, called sebocytes, dissolve and release sebum into the sebaceous glands.
Sebum travels through the follicular duct that connects the sebaceous gland to the hair follicle. The growing hair pulls the sebum up and onto the surface of the skin.
Sebum production fluctuates in response to changing hormone levels. Sex hormones traditionally thought of as male, especially testosterone, play a large role in regulating sebaceous gland activity.
Sebum production peaks shortly after birth and decreases within the first week of life. During puberty, testosterone floods the body, triggering another spike in sebum production. Testosterone and sebum levels naturally decline with age.
Sebum also transports fat-soluble antioxidants, such as vitamin E, to the skin’s surface. This action may help prevent oxidative skin damage.
Many components of sebum, including its fatty acids and squalene, have anti-inflammatory properties.
Components of sebum support skin health in several ways beyond combatting inflammation:
- Hydration: Sebum helps keep moisture inside the skin, which promotes skin hydration and flexibility.
- Antioxidant transport: Sebum transports fat-soluble antioxidants to the surface of the skin. Antioxidants are natural compounds that protect against the damaging effects of free radicals.
- Protection against microbes: Sebum is slightly acidic, with a pH of between 4.5 and 6.0. As a result, it helps prevent harmful pathogens, such as bacteria and viruses, from penetrating the skin.
Sebum production varies in response to age-related hormone fluctuations, certain medications, and lifestyle factors.
An overproduction of sebum can lead to oily skin. People with oily skin may notice that their pores look larger, and their skin appears greasy or shiny.
Excess sebum combined with dead skin cells can form a plug inside the pore, resulting in blackheads and pimples. This plug also traps bacteria in the pore, which can lead to inflammation.
Eventually, the blocked pore ruptures, spilling bacteria, sebum, and dead skin cells into nearby tissue and creating acne lesions that may be painful.
People can often control oily skin by using a gentle but effective skincare routine that includes products containing:
- beta-hydroxy acid
- benzoyl peroxide
- glycolic acid
- salicylic acid
The American Academy of Dermatology Association recommend that people with oily skin avoid oil- or alcohol-based cleansers. These products can irritate the skin, potentially triggering even more oil production.
Doctors can treat acne with:
- topical or oral antibiotics
- hormone therapy
- light therapy
- chemical peels
An underproduction of sebum can also cause problems. The following factors can suppress sebum production:
- exposure to allergens or harsh chemicals
- certain oral contraceptives, such as antiandrogens
- prescription retinoids, such as isotretinoin (Accutane)
- pituitary gland disorders
People with underactive sebaceous glands, or too little sebum, may have dry, flaky, and itchy skin. These symptoms may worsen if a person uses skincare products containing harsh chemicals.
Moisturizers containing ceramides or humectants can help relieve dry skin. Ingredients to look for include:
- hyaluronic acid
- alpha hydroxy acids
- jojoba oil
People can also treat dry skin at home by:
- exfoliating with a gentle face scrub
- using a humidifier to add moisture to the air
- bathing with warm instead of hot water
- avoiding skincare and haircare products that contain alcohol and artificial fragrances
A person might wish to consult a doctor if they have oily or dry skin that does not improve with over-the-counter treatments or home care strategies.
Also, contact a doctor if potentially concerning or uncomfortable skin symptoms arise, such as:
- persistent or numerous pimples
- inflamed pimples that cause emotional or physical discomfort
- recurring skin infections
- dryness, redness, or itchiness
- patches of dry skin that tear or bleed
The sebaceous glands produce an oily substance called sebum, which contributes the vast majority of lipids — fat molecules — to the skin’s surface. These surface lipids keep the skin hydrated and healthy.
Having too much or too little sebum can cause skin problems. Excess sebum production can lead to oily skin or acne, while an underproduction of sebum can result in dry, itchy, or flaky skin.
In either case, over-the-counter skin care products and home care strategies can help rebalance sebum levels. If these techniques are ineffective, a person might wish to contact a doctor.