Acne: Types, Causes and How to Treat It Properly
Acne (Acne Vulgaris) is the most common skin condition in the world, affecting more than 85% of people aged 12-24, and it is increasingly seen in adults as well. It affects not only skin health but also self-confidence and quality of life. Understanding the types and causes of acne helps you get the right treatment and better results.
What is acne?
Acne develops when hair follicles become blocked by oil and dead skin cells, together with an overgrowth of the bacterium Cutibacterium acnes (C. acnes) on the skin. This leads to inflammation in and around the follicle. Acne can appear anywhere there are oil glands, but it is most common on the face, neck, chest, back and shoulders.
Common types of acne
Acne falls into two main groups: non-inflammatory acne and inflammatory acne.
Non-inflammatory acne: Closed comedones (whiteheads) are small white or skin-coloured bumps caused by a blocked follicle that is still covered by skin. Open comedones (blackheads) are dark spots on the skin, caused by a blocked follicle that has opened, so the oil and melanin are exposed to air and turn black.
Inflammatory acne: Papules are small red bumps without pus. Pustules are bumps filled with white or yellow pus. Nodules are large, hard, painful lumps deep under the skin, and cysts are large fluid-filled sacs under the skin, which carry the highest risk of scarring.
Causes of acne
There are four main causes of acne: excess oil (sebum) production by the oil glands, follicles blocked by dead skin cells, an overgrowth of C. acnes bacteria, and the inflammation that follows. Triggers include hormones (especially during puberty and menstruation), stress, lack of sleep, pore-clogging cosmetics, certain medications, and foods high in sugar or dairy products.
How to treat acne properly
Acne treatment depends on the type and severity. Topical treatments include benzoyl peroxide, which kills C. acnes bacteria and reduces inflammation; salicylic acid, which helps clear blackheads and whiteheads; retinoids, which help skin cells shed and reduce blockage; and topical antibiotics, which reduce bacteria.
For more severe acne, a doctor may consider oral antibiotics, birth control pills for women whose acne is linked to hormones, or isotretinoin for very severe acne. Procedures are also available, such as chemical peels to help skin cells shed and reduce blackheads, corticosteroid injections for nodules, and lasers to kill bacteria and reduce inflammation.
When should you see a dermatologist?
See a dermatologist if your acne has not responded to home treatment within 2-3 months, you have large nodules or cysts, your acne is leaving scars or pits, it is affecting your mental well-being significantly, or it appears together with hair loss or unusual hair growth, which may point to a hormonal disorder.
About Siam Dermatology
Siam Dermatology is a specialist skin clinic with dermatologists who provide complete acne care, including topical and oral medications and procedures such as chemical peels, lasers and injections. The clinic is located in Samut Prakan. Consult a dermatologist today. Call +66 61 448 7000
References
1. Zaenglein AL, et al. (2016). Guidelines of care for the management of acne vulgaris. Journal of the American Academy of Dermatology, 74(5), 945-973.
2. American Academy of Dermatology (AAD). Acne Clinical Guidelines. aad.org
3. Kraft J, Freiman A. (2011). Management of acne. CMAJ, 183(7), E430-E435.
4. Williams HC, et al. (2012). Acne vulgaris. The Lancet, 379(9813), 361-372.
5. Thiboutot D, et al. (2009). New insights into the management of acne: An update from the Global Alliance. Journal of the American Academy of Dermatology, 60(5 Suppl), S1-50.
Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed 16 July 2026
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