What Actually Causes Acne and Blemishes and How to Treat Them Properly

Acne is one of the most common skin conditions in the world, and also one of the most misunderstood. People spend years using the wrong treatments for the wrong type of breakout and wonder why nothing works. A blackhead and a cystic nodule are both called acne, but they have different causes and respond to completely different treatments.

This guide covers how acne forms, which treatments are actually supported by evidence, and how to build a routine that clears skin without wrecking the barrier in the process.

What Actually Causes Acne?

Acne forms when pores become clogged. That sounds simple, but the clogging process involves a few factors working together:

Excess sebum: The skin produces oil through sebaceous glands. When sebum production is high, often from hormonal influences, it can accumulate in pores.

Dead skin cells: Normally, dead skin cells shed from the surface. In people prone to acne, these cells can stick together and block pores instead of sloughing off cleanly.

C. acnes bacteria: This bacteria lives on most people's skin without causing problems. In a clogged, oxygen-deprived pore, it multiplies and triggers inflammation, which is what turns a blocked pore into a red, painful pimple.

Hormones: Androgens, particularly during puberty, around the menstrual cycle, or from conditions like PCOS, directly increase sebum production. Hormonal acne typically shows up along the jaw and lower face.

Types of Acne: Why It Matters for Treatment

Blackheads and whiteheads (comedonal acne): These are clogged pores without bacterial involvement or significant inflammation. Blackheads are open, and the dark color comes from oxidized melanin, not dirt. Whiteheads are closed. These respond well to exfoliation and retinoids.

Papules and pustules (inflammatory acne): Red, raised bumps. Pustules have a white center. These involve bacteria and inflammation. Benzoyl peroxide and antibiotics are effective here.

Nodules and cysts: Large, deep, painful lesions. These form deeper in the skin and almost always require professional treatment. Over-the-counter products alone are rarely enough for severe cystic acne.

The Two Main Over-the-Counter Treatments

Salicylic Acid (BHA)

Salicylic acid is a beta-hydroxy acid derived originally from willow bark. What makes it useful for acne is that it is oil-soluble, meaning it can penetrate into pores and dissolve the buildup of dead cells and sebum from inside. Most chemical exfoliants cannot do this.

It is most effective for non-inflammatory acne, blackheads, whiteheads, and clogged pores. It also helps with overall skin texture and pore appearance over time. Over-the-counter concentrations are typically 0.5% to 2%. Higher concentrations are used in clinical chemical peels.

For daily use, a 2% salicylic acid cleanser or leave-on product is a good starting point. It can cause dryness, so starting slowly and following with a non-comedogenic moisturizer helps.

Benzoyl Peroxide

Benzoyl peroxide works differently. Rather than exfoliating, it releases oxygen into the pore, creating an environment where C. acnes bacteria cannot survive. It also has some anti-inflammatory effects. This makes it particularly effective for inflammatory acne like papules and pustules.

Available in concentrations from 2.5% to 10%, studies suggest that higher concentrations do not provide meaningfully better results but do increase irritation. The 2.5% formulation is a reasonable starting point for most people.

Worth noting: benzoyl peroxide will bleach fabric. White pillowcases, towels, and shirts are strongly recommended if you use it at night.

Which One Should You Use?

If your acne is mostly blackheads and clogged pores with little redness: salicylic acid.

If your acne is mostly red, inflamed papules and pustules: benzoyl peroxide.

If you have both: many people alternate them. Salicylic acid in the morning, benzoyl peroxide spot treatment at night. Or alternate days. Using both at the same time in the same step can cause significant irritation.

Retinol and Retinoids for Acne

Retinoids are also effective for acne because they accelerate cell turnover, which prevents dead cells from accumulating and clogging pores. They also reduce inflammation over time and improve the appearance of post-acne marks.

Prescription tretinoin (Retin-A) is particularly well-studied for acne. Over-the-counter retinol requires more time to show results but is more accessible. Adapalene (0.1%) is now available over the counter in many countries and is gentler than tretinoin while still being effective for both acne and anti-aging.

Retinoids should not be layered with benzoyl peroxide in the same routine step. They can be used on alternating nights, or benzoyl peroxide can be used in the morning while retinoids are applied at night.

Building an Acne-Focused Skincare Routine

Morning Routine

Gel or foam cleanser (salicylic acid if needed), niacinamide serum (helps regulate sebum and reduce redness), lightweight oil-free moisturizer, SPF 30+ sunscreen. Avoid heavy oils and thick cream formulas in the morning.

Evening Routine

Cleanser, treatment step (benzoyl peroxide spot treatment or salicylic acid toner depending on acne type), retinol or adapalene 3 nights per week, oil-free moisturizer.

Common Mistakes That Make Acne Worse

Over-cleansing: Washing your face four or five times a day strips the skin barrier and causes it to overproduce oil in response. Twice a day is the right frequency for most people.

Skipping moisturizer: Acne-prone skin needs moisture. When dehydrated, skin produces more sebum to compensate, which makes breakouts worse. Use a lightweight, non-comedogenic moisturizer.

Popping pimples: Squeezing a pimple pushes bacteria and debris deeper into the pore, increases inflammation, and significantly raises the risk of scarring. Acne patches (hydrocolloid bandages) are a better option for surface pimples. They draw out fluid overnight without causing trauma.

Switching products too frequently: Acne treatments need 6 to 8 weeks of consistent use before results are visible. Many people switch to something new at the 3-week mark, just before anything would have actually changed.

Using too many actives at once: Layering salicylic acid, benzoyl peroxide, retinol, and an acid toner all in the same routine leads to barrier damage, which causes more breakouts, not fewer.

When Over-the-Counter Products Are Not Enough

If you have tried a consistent routine with salicylic acid or benzoyl peroxide for two to three months and seen no improvement, or if your acne is cystic and painful, it is worth seeing a dermatologist. Prescription options including topical retinoids like tretinoin, oral or topical antibiotics, or hormonal treatments like spironolactone for women are significantly more effective for moderate to severe acne.

There is no shame in needing more than over-the-counter treatment. Some types of acne genuinely require prescription intervention, and the sooner you address it, the less likely you are to be left with lasting scars.

Dealing With Post-Acne Marks

Post-inflammatory hyperpigmentation, the dark spots that remain after a pimple heals, is one of the most frustrating parts of acne. These are not scars but temporary discoloration from inflammation. They fade on their own but can take months.

Vitamin C, niacinamide, azelaic acid, and retinol all help speed up the fading process. Sunscreen is critical here too: UV exposure makes hyperpigmentation darker and makes it take longer to fade.

True acne scars, which have a textural component, require professional treatment. Chemical peels, microneedling, and laser treatments are the most effective options, depending on scar type.

The short version: treat the acne first. Then address the marks.