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Acid treatment, known in Chinese as "shua suan" (brushing acid), is an in-clinic skin procedure in which a measured concentration of acid is applied to the skin for a short, timed contact, then neutralized or removed. Clinics typically use salicylic acid, fruit acids (AHAs), or blended formulas to manage acne, closed comedones, and lingering post-acne marks; it sits at the superficial end of the broader chemical peel family.
The concerns most often brought to acid treatment are recurring breakouts, closed comedones, blackheads, oily skin, and the red or dark marks left behind after acne subsides. The face is the usual treatment area, though some people also treat the chest or back. For orientation: chemical peel is the medical umbrella term spanning different depths, while the low-strength AHA peels offered in beauty salons are its gentlest, cosmetic form; this entry focuses on the in-clinic middle ground aimed at acne and post-acne marks.
What acid treatment can do is speed up the turnover of the outermost skin layer, help unclog pores, and gradually smooth texture over a course of sessions; shallow post-acne marks may also fade faster. What it cannot do is equally clear: depressed, pitted scars call for other technologies, severe cystic acne is not managed by acids alone, and pores are not permanently shrunk. A single session usually changes little—results depend on regular, well-spaced repetition.
Acids work by loosening the bonds between dead cells in the stratum corneum so they shed faster. Salicylic acid is oil-soluble, travels into pores to clear sebum, and has a mild anti-inflammatory effect, which is why it is favored for acne-prone skin; fruit acids (AHAs) are water-soluble and act mainly on the surface; blended formulas combine the two. A session typically involves cleansing and degreasing, applying acid zone by zone, timed observation of the skin's response, then neutralizing or removing the acid, followed by soothing care and strict sun protection.
During application, tingling, warmth, or a mild burning sensation is common, and the practitioner adjusts contact time based on how the skin reacts. Immediately afterward the skin may look flushed and feel tight; over the next few days mild dryness and light flaking can follow, and acne-prone skin sometimes goes through a brief purge in early sessions. Improvement is gradual—sessions are usually spaced weeks apart, and texture changes tend to become noticeable partway through a multi-session course.
The typical candidate is an adult with oily, congestion-prone skin—recurring closed comedones, small breakouts, shallow post-acne marks, or rough texture. A worthwhile consultation should cover your skin type and any history of sensitivity, which acid and what concentration suit you, roughly how many sessions and at what interval, whether current skincare—especially retinoids and other actives—should be paused, and what a realistic improvement looks like on your skin.
It is not for everyone. Treatment should be avoided when the skin barrier is compromised, when eczema, dermatitis, or an active infection is present in the area, or shortly after significant sun exposure. People allergic to salicylates such as aspirin should not receive salicylic acid. Pregnancy or breastfeeding, current oral isotretinoin or other potent medications, and a tendency to keloid scarring should all be disclosed beforehand so the clinician can judge whether—and how—to proceed. Highly sensitive skin, if treated at all, usually calls for lower strengths and longer intervals.
Expected reactions include stinging during treatment and redness, tightness, dryness, and light flaking for a few days afterward, all of which typically settle on their own. Recovery care centers on gentle cleansing, extra moisturization and barrier repair, strict sun protection, and pausing scrubs, retinoids, and other acids as advised. The brief purge that some acne-prone skin experiences early on usually eases as the course progresses.
Less common problems include prolonged redness, irritant dermatitis, post-inflammatory hyperpigmentation—a higher risk with deeper skin tones or inadequate sun protection—and chemical burns, blistering, or even scarring when the concentration is too high or the contact time too long; overly frequent sessions can also damage the skin barrier. For these reasons, higher-concentration acid treatment is a medical procedure: choose a licensed medical institution where it is performed by, or under the guidance of, a qualified physician, rather than escalating strengths on your own at home.
Contact the treating clinician promptly if you develop severe or worsening pain, blisters, oozing, a spreading rash, pigmentation that darkens instead of fading over the following weeks, or persistent redness and sensitivity. This article is general information only; it is not a diagnosis and cannot replace an in-person professional assessment—whether and how to pursue acid treatment should follow from a face-to-face consultation.