What Is Salicylic Acid (BHA)? Use for Acne and Blackheads

What salicylic acid does: This oil-soluble beta hydroxy acid (BHA) can help reduce the appearance of blackheads and whiteheads by loosening the buildup inside pores. Over-the-counter products typically contain 0,5-2%. Initially, once a day or a few times a week is enough; if dryness occurs, reduce the frequency. Avoid applying it to large areas. Before using it during pregnancy, while breastfeeding, and on young children, consult a doctor.

Why does oil solubility make a difference?

Most acids in peels and toners are water-soluble. Salicylic acid is oil-soluble. Since the inside of a pore is an oily environment, it can penetrate into the pore more easily than water-soluble acids and target the plug made of oil and dead cells. Because blackheads and whiteheads form exactly from this plug, it is most recommended for these concerns.

Its effect has two basic aspects:

• Keratolytic effect: It softens the keratin protein in the upper layer and makes it easier for dead cells to shed.
• Shedding pattern inside the pore: It helps prevent blockage by reducing cell buildup in the channel.

What does it not do? It does not permanently shrink oil glands, does not change pore size, and does not reach deep, painful acne. Its effect is also limited when it stays on the skin only briefly in a cleanser.

What does salicylic acid do? How strong is the evidence in acne?

Its widespread use does not show that its evidence is strong. A comprehensive systematic review examining over-the-counter ingredients for acne assessed 49 studies and 3.880 participants across six different ingredients. On the salicylic acid side, studies are few and small: in a 46-person study comparing it with tretinoin, the results showed little or no difference, but certainty was low. A study of 41 people comparing it with benzoyl peroxide did not measure participants' overall assessment. The review's common message is clear: clinical benefit is uncertain, and more robust studies are needed.

So trying salicylic acid is reasonable, but expecting it to resolve severe acne is not. The table below puts this into practice.

The causes of acne are explained in detail in the why acne forms article. Remaining dark marks and scars are a different topic; see the acne scar article.

Percentages: Which percentage is used for what?

Salicylic acid is used in a very wide range, from 0,5% to 30%, but not all of these are products you will apply to your face.

The same 2% does not do the same thing in a cleanser and in a serum. A cleanser stays on the skin briefly and is rinsed off, while a serum stays on the skin until the next wash. So instead of choosing by 'the 2% is the strongest', look at the product type. If the label does not state a concentration, starting with a rinse-off product is a more cautious path.

Sample frequency by product type

Although it is said that twice a day can be used by most people, this is not necessary at the start. The table below is a starting point derived from the general caution rule; if it conflicts with the product label, follow the label.

Oily skin may tolerate more frequent use better; for dry and sensitive skin, staying in the left column of the table is generally enough.

Rules to follow when adding to your routine

1. Start with a single product. If cleanser, toner and serum all contain salicylic acid at the same time, the skin takes on too much. Test the new product first on the inner arm or elbow crease, twice a day, for 7-10 days.
2. Do not skip moisturizer. Even on oily skin, dryness does not solve the sebum problem; it strains the barrier. The article on moisturizer selection explains options that do not clog pores.
3. Keep using sunscreen. For salicylic acid, photosensitivity has not been shown as clearly as with AHAs; in a mouse study a protective effect was even seen. But that is not a result for people; with any product that can thin the upper layer, you need daytime protection. Reapply a broad-spectrum sunscreen of at least SPF 30 every 2 hours; details are in the sunscreen guide.
4. Do not use together with retinol. Both dry the skin. Let salicylic acid go on in the morning and retinol in the evening or on alternate days.
5. Do not scrub. Pressing hard on the pad or scrubbing the face does not open the plug; it causes irritation.
6. Give it time before deciding. In the first weeks, small pimples may temporarily increase. If stinging, itching and redness do not accompany this, it may be an expected situation. 8 weeks is a reasonable starting point for evaluation.

Salicylic acid or another agent?

Depending on your goal, salicylic acid may not be the first choice. The table below sets the options side by side; the use of prescription ones is decided by the doctor.

On the label the ingredient appears as "Salicylic Acid," and "BHA" appears in marketing language. Salicylic acid is historically associated with willow bark, but seeing willow bark extract on the list does not show that the product contains the same amount of salicylic acid.

Common mistakes with salicylic acid

• Using three products in succession. Cleanser, toner and serum together do not bring faster results; they mostly bring more dryness.
• Taking tightness as a sign that it is working. Dry skin is skin with a tired barrier.
• Stopping moisturizer because your skin is oily. It does not solve the problem and may increase irritation.
• Applying a facial product generously to the back and chest. As the area grows, absorption also increases.
• Expecting results in a few days. Opening existing plugs and preventing new ones takes time; frequently changing products also disrupts your evaluation.
• Squeezing pimples. While using acids, the skin can be damaged more easily; the risk of scarring and dark spots increases.

Risks: Irritation, allergy and salicylate poisoning

Salicylic acid is well tolerated by most people. However, the most common problems are burning, dryness and peeling, especially on cracked skin and at high concentrations. If moderate or severe irritation, redness or a feeling of heat occurs, stop using it and consult your doctor.

• Allergy: It is rare, but contact allergy has been reported, and anaphylaxis cases exist, although very rarely. If you have an allergy to aspirin or salicylates, consult your doctor before use. Call for emergency help in case of swelling or shortness of breath.
• Salicylism (salicylate poisoning): Rare with products applied to the skin. The risk increases with application over a large area, at high concentration, under occlusion (covered with a bandage), and in children. Symptoms: dizziness, ringing in the ears, nausea, vomiting, diarrhea, rapid breathing, headache, severe drowsiness, confusion. If these symptoms occur, wash off the product and get emergency help.
• Cracked and injured skin: Absorption and irritation increase. Do not apply to these areas.

Also do not use products that cover a large part of the body (some peels, large-area lotions) carelessly. A product suitable for a small area of the face may not be suitable for the whole body.

Pregnancy, breastfeeding and children

In this section we draw a cautious framework; consult your doctor for a personal decision.

• Pregnancy: Low concentrations (2% and below), applied to a small area, for short-term use, are said to generally be considered low risk, but there are few solid studies in pregnant women. Because salicylic acid can be absorbed through the skin, risks and benefits should be discussed with a doctor. Avoid application over large areas, high concentrations, closed application, and peeling procedures.
• Breastfeeding: It is often considered acceptable in medication safety sources, but do not apply the product to areas that will contact the baby, and consult your doctor.
• Children: Normally not used in children under two years old. Greater absorption and more irritation are expected in small children than in adults. European assessments call for caution with products aimed at children under three as well. If it will be used for acne in adolescents, first get the opinion of a dermatologist or pediatrician.

If salicylic acid is not enough

Instead of continuing to change products, see a dermatologist if:

• If there is no difference after regular use for 8-12 weeks
• If your pimples are deep, painful or leave scars
• If you have acne that starts suddenly in adulthood, or comes with irregular periods or hair growth
• If burning, stinging and peeling develop with every product
• If there is widespread rash, wounds or flaking on the skin and you are not sure whether it is acne

The doctor will discuss prescription topical or oral treatment options if necessary. The dose and duration of these treatments are determined only by examination.