Acne has several causes that act together: the oil glands produce too much oil (stimulated by androgen hormones), abnormal shedding of skin cells blocks the pores, and Cutibacterium acnes bacteria multiply in the blocked pores. Other factors such as stress, genetics and pore-clogging products also play a part.

Can I squeeze acne myself?

Not recommended. Squeezing acne without the right technique pushes the pimple deeper into the skin, increases inflammation, and raises the chance of scars and dark marks that are very slow to fade. If you want a pimple drained, have a dermatologist perform Comedone Extraction with sterile instruments.

Is isotretinoin (Accutane) dangerous?

Isotretinoin is safe and highly effective when used under the care of a specialist dermatologist. The most important precaution is that it must never be used during pregnancy, because it can cause birth defects. The doctor will also monitor blood lipids and the liver with blood tests during treatment. The AAD 2024 guidelines confirm that this medicine is the standard for severe acne that does not respond to other treatments.

How is fungal acne different from ordinary acne?

Fungal acne (Fungal Acne / Malassezia Folliculitis) looks similar to inflamed acne, but it is caused by yeast in the hair follicles, not bacteria. Treatment is completely different: ordinary acne medicines do not work and an antifungal medicine is needed. An accurate diagnosis therefore requires seeing a dermatologist.

How is adult acne different from teenage acne?

Adult acne (Adult Acne) is common in women aged 25-40 and is usually linked to hormones, such as the menstrual cycle, PCOS, birth control pills or stress. Pimples tend to appear on the chin, jawline and neck more than on the forehead. Treatment may need to include correcting hormones, not just topical medicine.

Which acne cream brand should I choose?

There is no single best acne cream for everyone, because acne has different causes. Ingredients with clear evidence include benzoyl peroxide (BPO), adapalene (a retinoid) and azelaic acid. However, choosing the wrong type or strength may irritate the skin or make acne worse, so consult a dermatologist before choosing one.

Do acne and post-acne dark marks (Post-inflammatory Hyperpigmentation) need different treatment?

Yes. Dark marks after acne are not scars but a temporary change in skin colour. They are treated with azelaic acid, niacinamide or vitamin C together with daily sunscreen. Acne scars (Acne Scar) that are pitted or raised need procedures such as laser or microneedling, performed by a dermatologist.

Acne Treatment: Causes, Types and Treatment Options from a Dermatologist

6 days ago

5 min read

Acne: Causes, Types, Treatment and When to See a Dermatologist

Acne is the most common skin condition in the world. It is not only a problem for teenagers: in some groups, more than 50% of adults aged 20 and over are affected, especially women with hormonal imbalance. Severe or persistent acne affects not only the skin but also confidence and quality of life.

This article brings together up-to-date medical information based on the 2024 American Academy of Dermatology (AAD) guidelines and DermNet NZ, to help you understand acne correctly, from its causes and types to treatment and prevention.

Medically reviewed by Dr. Patara Voravutinon Diplomate, Thai Board of Dermatology, Medical Council licence no. 54323

Important notice: This article provides general information for educational purposes. It is not medical advice and cannot replace an examination and diagnosis by a specialist dermatologist. If you have any concerns about your skin, please consult a doctor directly.

What is acne?

Acne (Acne Vulgaris) is a chronic inflammatory condition of the hair follicles and oil glands. It occurs when pores become blocked and the bacteria Cutibacterium acnes (formerly called Propionibacterium acnes) multiply, causing anything from simple clogged pores to inflamed acne or painful cystic acne.

Acne most often appears where there are the most oil glands: the face, chest, back and shoulders.

Causes of acne

Acne does not have a single cause. It results from several factors working together:

1. Overproduction of oil by the oil glands (Excess Sebum)

Androgen hormones stimulate the oil glands to produce more sebum (the skin's natural oil) than normal. The excess sebum blocks the pores and becomes food for bacteria.

2. Abnormal shedding of skin cells (Abnormal Keratinization)

Dead skin cells do not shed normally. Instead they stick to sebum and form a plug (Comedone) in the pore.

3. C. acnes bacteria

These bacteria live on everyone's skin, but when a pore is blocked they multiply quickly and trigger inflammation.

4. Hormones (Hormonal Fluctuations)

Teenagers: sex hormones surge during puberty.
Women: the time before a period, pregnancy, stopping birth control pills, or PCOS.
Adults: stress makes cortisol stimulate the oil glands.

5. Pore-clogging products (Comedogenic Products)

Some creams, foundations or oils contain ingredients that block pores. Choose products labelled "Non-comedogenic" or "Oil-free".

6. Other factors

Genetics: if a parent had severe acne, the chance of having it is higher.
Certain medicines: steroids, lithium, anti-seizure medicines.
Accumulated stress and insufficient sleep.

Note: Chocolate or fatty foods are not a direct cause, but a high-sugar, high Glycemic Index diet may make acne worse in some people.

Types of acne

Acne falls into two main groups, non-inflammatory and inflammatory acne, and each type needs a different treatment approach.

Acne type	Appearance	Inflammation	Pain	Risk of scarring
Whitehead (Closed Comedone)	Small white bumps covered by skin	None	Not painful	Low
Blackhead (Open Comedone)	Dark pores caused by oxidation, not dirt	None	Not painful	Low
Pustule	Red bump with a yellow-white pus head	Yes	Slightly painful	Moderate
Nodule / Cystic acne (Nodule / Cystic Acne)	Hard lump deep under the skin, or a cyst filled with pus	Severe	Very painful	High: often leaves scars
Papule	Raised red bump without a pus head	Yes	Can be painful	Moderate

Why does the type matter? Clogged pores respond well to retinoids, whereas cystic acne needs oral medication or isotretinoin, and treating it the wrong way may leave permanent scars.

Acne treatment by severity (AAD 2024 guidelines)

The AAD 2024 guidelines recommend choosing acne treatment according to the severity and type of acne. A dermatologist will assess you and adjust the plan to suit your skin and the cause of your acne, rather than simply prescribing medicine for the symptoms.

Mild to moderate acne (clogged pores / mildly inflamed acne): topical medicines

Benzoyl peroxide (Benzoyl Peroxide, BPO) is a first-line treatment with clear evidence. It kills C. acnes directly and reduces antibiotic resistance. It can be used as a wash-off or leave-on product.

Retinoids (vitamin A) such as tretinoin, adapalene and tazarotene help speed up skin cell turnover, open blocked pores and reduce the formation of new acne. Start gradually because they can cause irritation at first. Use them at night and avoid sunlight.

Topical antibiotics such as clindamycin reduce inflammation. They are usually combined with BPO to prevent resistance and should not be used alone for more than 3 months.

Others recommended conditionally: azelaic acid (good for darker skin and for preventing dark marks), salicylic acid (cleans out pores)

Moderate to severe inflammatory acne: oral medicines

Oral antibiotics Doxycycline or minocycline reduce inflammation and bacteria throughout the body. Use them for the shortest effective time, generally no longer than 3 months, and always together with a topical medicine (BPO or a retinoid) to prevent resistance. The AAD 2024 guidelines advise against using oral antibiotics as monotherapy or for longer than necessary.

Combined oral contraceptives For women whose acne is linked to hormones, these help reduce androgens.

Spironolactone An anti-androgen medicine suitable for women whose acne appears around the chin and jawline or before their period.

Isotretinoin (Accutane)

⚠️ Prescription medicine: must be used only under the care of a specialist dermatologist. Do not buy and use it yourself.

Isotretinoin is the strongest form of vitamin A. It reduces sebum production, blockage and inflammation comprehensively. It is recommended for severe cystic acne, acne that has not responded to other medicines, or acne that is causing scars. Important precautions:

Must never be used during pregnancy. It causes serious birth defects (Teratogenic). Reliable contraception is required throughout treatment and for 1 month after stopping.
Blood tests (blood lipids, liver) are needed before starting and during treatment.
The doctor will set the dose and duration to suit each person. Do not adjust the dose yourself.

Acne procedures performed by a specialist dermatologist

Acne extraction and cyst drainage (Acne Extraction / Comedone Extraction): The doctor uses sterile instruments to open and drain clogged acne, which lowers the risk of scarring compared with squeezing it yourself.
Corticosteroid injection: For a single cystic pimple that needs to shrink quickly.
Laser / Light Therapy: Helps reduce bacteria and inflammation.
Chemical Peel: Salicylic acid peels or glycolic acid peels speed up skin cell turnover and reduce dark marks.

How long does acne take to clear? What you need to know

The question patients ask most often is "How long until I see results?" The dermatologist's answer is clear:

Time	What happens
2-4 weeks	You may start to see small changes. Some people may have a temporary flare of new pimples (Purging) from retinoid-type medicines. This is a normal reaction.
6-8 weeks	Inflammation decreases and new pimples are 30-50% fewer.
3-4 months	Clear results, with a significant reduction in acne.
6 months or more	Skin looks smoother and dark marks fade (with consistent treatment).

The reason you have to wait is that the skin cell cycle (Skin Cell Cycle) takes about 28 days. Treatment needs to go through several cycles before results show. No medicine or product can clear acne within a few days.

If there is no improvement after 12-14 weeks of treatment, that is a sign the treatment plan needs to be adjusted, and a dermatologist can assess you and change the approach.

Written by Dr. Patara Voravutinon, Dermatologist · Last reviewed July 16, 2026