Understanding Sebaceous Glands: Function, Anatomy, and Skin Health
Updated: 2 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What are sebaceous glands?
Sebaceous glands are tiny glands, usually attached to hair follicles, that release an oily substance called sebum. [1] Made of fats such as cholesterol and fatty acids, sebum forms a protective coating that keeps skin from drying out, reduces friction and helps defend against bacteria and fungi. [1] The glands are found everywhere except the palms and soles. [1]
What the research says
Sebum does more than make skin oily, and it changes over the lifespan. A review of sebaceous gland function reports that the number of glands stays about the same throughout life while their size tends to increase with age, that sebum output rises sharply at birth and again from about age 9 until the adult level is reached around age 17, and that sebaceous lipids help keep the skin barrier intact and have innate antimicrobial activity. Excess sebum is a major factor in acne, which may be a primarily inflammatory disease (Zouboulis, Clin Dermatol, 2004) [2].
The evidence for washing and cleansers in acne is thin. A systematic review of 14 prospective studies (671 participants) of face washing and over-the-counter cleansers, including salicylic acid cleansers, found too few well-performed studies to make reliable recommendations, so gentle, consistent care and professional advice for persistent acne are sensible (Stringer et al., J Dermatolog Treat, 2018) [3].
What does sebum from the sebaceous glands do?
The main job of sebaceous glands is to produce and release sebum. This oily substance is a mix of lipids that serves several protective purposes. [1] Without enough sebum, skin becomes dry, brittle, and more vulnerable to environmental damage.
Sebum Component | Role in Skin Health |
Fatty acids and glycerides | Help the skin hold moisture and provide natural lubrication. |
Wax and squalene | Help form a protective barrier against outside irritants. |
Cholesterol | Contributes to the structure of the skin’s surface. |
Beyond lubrication, sebum acts as a biological shield. It limits moisture loss, keeps hair from becoming brittle, and helps protect against harmful bacteria and fungi. [1] [2] Sebum also contributes to individual body odor. [1]
What is the anatomy and lifecycle of sebaceous glands?
Sebaceous glands sit in the dermis, the second layer of the skin. [1] Most are connected to hair follicles and release sebum into the follicle, from where it travels to the skin’s surface. [1] Some glands are not attached to a hair follicle and open directly onto the skin surface, such as in the lips, the inside of the nose, and the genital area. [1]
Distribution and Concentration
You have thousands of sebaceous glands. [1] They are most concentrated on the face and scalp, which is why these areas tend to get oily. [1] Sebaceous glands are absent from the palms of the hands and the soles of the feet. [1]
Production Throughout Life
Sebum production is not constant and changes with age.
Birth to childhood: Glands activate at birth, but production is slow through early childhood. [1]
Puberty: Hormonal changes trigger a large increase in sebum, which often leads to teenage skin problems. [1] [2]
Adulthood: Production usually settles to normal levels. [1]
Later years: After about age 70, sebum production slows gradually. [1]
What are common sebaceous gland conditions and their signs?
When sebaceous glands are overactive or blocked, several skin conditions can result. Knowing about them is the first step toward good management and treatment.
Acne: The best-known condition, in which pores are blocked by a sebum plug, leading to pimples. [1] See our complete guide to acne for more.
Sebaceous hyperplasia: A harmless condition in which overactive glands cause small, pale bumps on the skin.
Sebaceous cysts: Movable lumps that form under the skin. [1] Many lumps called sebaceous cysts are actually epidermoid or pilar cysts that arise from hair follicles and are filled mostly with keratin, so a clinician should confirm what a lump is.
Sebaceous filaments: Small collections of sebum and dead skin cells that can make pores look larger. They are often confused with blackheads. [1]
Sebaceous carcinoma: A rare and serious cancer that typically appears as a firm yellow lump, often on the eyelid. [1]
How can you keep your sebaceous glands healthy?
Healthy sebaceous glands depend on a consistent skincare routine that manages oil without stripping the skin of its natural defenses.
Cleansing: Use a gentle cleanser daily to remove excess sebum and help prevent clogged follicles. [1]
Targeted ingredients: Products containing salicylic acid can help keep pores clear. [1]
Moisturizing: Even oily skin benefits from daily moisturizer, which helps prevent glands from overcompensating for dryness.
Protection and hydration: Apply sunscreen when outdoors and stay hydrated by drinking water through the day. [1]
Care Pillar | Actionable Step |
Cleansing | Use a gentle, non-stripping face wash morning and night. |
Exfoliation | Use salicylic acid to help loosen sebum plugs and dead skin. |
Hydration | Drink water regularly to support overall skin health. |
Sun safety | Use a non-comedogenic sunscreen to protect the skin from UV damage. |
Conclusion
Sebaceous glands are essential for keeping the skin moist and protected. Overactivity can cause oily skin or acne, but their basic job of preventing infection and protecting the skin barrier is vital. With a balanced care routine and attention to early signs of gland-related conditions, you can keep your skin healthy and resilient at every stage of life.
What are the next steps for sebaceous gland health?
If you notice unusual lumps, persistent acne, or changes in your skin’s texture, see a healthcare provider or dermatologist. Early diagnosis of conditions such as cysts or rare carcinomas is important for effective treatment. Book a skin examination if something looks or feels new, changing, or concerning.
Frequently Asked Questions
What do sebaceous glands produce?
Sebaceous glands produce sebum, an oily substance made of lipids such as cholesterol and fatty acids.
Where are most sebaceous glands located?
The highest concentrations are on the face and scalp.
Are there places without sebaceous glands?
Yes. They are absent from the palms of the hands and the soles of the feet.
How does sebum protect the skin?
Sebum lubricates, limits moisture loss, and helps guard against bacteria and fungi.
Why is acne common during puberty?
Puberty triggers a large increase in sebum production, which can clog pores.
What is a sebaceous cyst?
A sebaceous cyst is a movable lump under the skin. Many are actually epidermoid or pilar cysts, so it is best to have a clinician identify the lump.
How do sebaceous glands release sebum?
Most release sebum into the hair follicle, and it travels up to the skin’s surface.
What is the difference between sebum and sweat?
Sebum is oily and comes from sebaceous glands. Sweat is watery and comes from sweat glands.
Can retinoids shrink sebaceous glands?
Retinoids can make pores look smaller and lower sebum production, but they do not shrink the glands themselves.
What are sebaceous filaments?
Sebaceous filaments are collections of sebum and skin cells that fill pores and often show up as small dots on the nose.
Is sebaceous carcinoma common?
No. It is a rare cancer that often appears as a firm yellow lump on the eyelid.
Should I skip moisturizer if I have oily skin?
No. Skipping moisturizer can leave skin dry, and a daily moisturizer is part of a healthy routine even for oily skin.
How does age affect sebum production?
Production rises in puberty, settles in adulthood, and slows gradually after about age 70.
What ingredients help with clogged pores?
Salicylic acid is commonly used to help loosen sebum plugs and keep pores clear.
Are mammary glands a type of sebaceous gland?
No. Mammary glands are specialized for milk production, not sebum.
Related Reading
Sebaceous Cysts (Epidermal Inclusion Cysts): What They Are, When to Treat Them, and When to Leave Them Alone — A Complete Guide explains common skin cysts and when they need treatment.
Seborrheic Dermatitis (Dandruff): Symptoms, Causes, Diagnosis & Treatment — Complete Guide covers flaky, itchy rash in oily areas of skin.
Sebaceous Carcinoma: Complete Guide to Symptoms, Causes, Diagnosis, and Treatment describes a rare cancer that starts in the oil glands.
Comedonal Acne: What It Is, Why It Happens, and How It's Treated explains blackheads and whiteheads from clogged oil glands.
References
Cleveland Clinic. Sebaceous Glands. Cleveland Clinic. December 14, 2022. https://my.clevelandclinic.org/health/body/24538-sebaceous-glands
Zouboulis CC. Acne and sebaceous gland function. Clin Dermatol. 2004;22(5):360-366. PMID: 15556719. https://doi.org/10.1016/j.clindermatol.2004.03.004
Stringer T, Nagler A, Orlow SJ, Oza VS. Clinical evidence for washing and cleansers in acne vulgaris: a systematic review. J Dermatolog Treat. 2018;29(7):688-693. PMID: 29460655. https://doi.org/10.1080/09546634.2018.1442552
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this article.
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