Beta-Hydroxy Acid (BHA) Treatments#

Beta-hydroxy acids (BHAs) are an oil-soluble family of exfoliating acids. Unlike most other skincare acids, BHAs dissolve through the oily layer at the top of the skin and reach inside pores. The most common BHA in skincare is derived from willow bark or made synthetically. It is used for:

• Unclogging blocked pores (blackheads, whiteheads)
• Reducing the small inflamed bumps of mild-to-moderate acne
• Smoothing rough texture
• Dissolving thickened skin (the basis for OTC wart, callus, and corn removers, which use much higher concentrations)

In skincare it is most useful for people with oily, combination, or acne-prone skin.

BHAs work in three ways:

1. Penetrate oil and reach pore lining - because they are oil-soluble, they get inside pores that water-based acids cannot reach.
2. Loosen dead skin cells - they break the bonds between the cells lining the pore, allowing the cell debris and oil to clear out.
3. Calm inflammation - they have a mild anti-inflammatory effect, which helps reduce the redness and swelling of active acne.

Because they work inside pores rather than only on the skin's surface, BHAs tend to give a noticeable improvement in blackheads and oily areas (forehead, nose, chin).

The big difference is where each acid works:

• AHAs are water-soluble. They exfoliate the surface and are good for dullness, fine lines, and dark marks.
• BHAs are oil-soluble. They work inside pores and are good for acne, blackheads, and oily skin.

In a TeleTest cosmetic-dermatology plan, AHAs and BHAs are sometimes used together on alternating days to address both surface texture and pore congestion.

For at-home use:

• 0.5 to 1 percent - sensitive skin or first-time users; cleansers and toners.
• 1 to 2 percent - regular use for acne-prone or oily skin.
• 2 percent leave-on - daily spot treatment or full-face for established users.
• 10 percent and above - professional in-clinic peels, or OTC wart/callus removers used only on those specific spots, not on the face.

Daily use at 0.5 to 2 percent is generally safe long-term for oily skin. If your skin is on the drier side, every other day is a better start.

A typical routine:

1. Cleanse with a gentle cleanser (this can itself be a BHA cleanser).
2. Apply a BHA toner or leave-on product to clean, dry skin - focus on oily zones and areas with blackheads.
3. Wait one to two minutes for it to absorb.
4. Moisturize with a non-comedogenic moisturizer (one that does not clog pores).
5. In the morning, finish with sunscreen (SPF 30 or higher) - even though BHAs themselves do not significantly increase sun sensitivity, daily sunscreen still protects your skin.

Most people can use it once daily. Sensitive skin: start every other day.

These pair well with BHAs:

• Niacinamide - calms redness and supports the skin barrier.
• Hyaluronic acid - hydrates without adding oil.
• Ceramide-based moisturizers - help offset any dryness.
• Benzoyl peroxide - works on a different cause of acne, but apply at a different time of day to reduce dryness.

Layered at the same time, these tend to over-exfoliate:

• AHA leave-on products - use on alternate nights.
• Vitamin A products (OTC retinol or prescription retinoid) - alternate nights, or use BHA in the morning and vitamin A product at night.
• Strong physical scrubs - the BHA is doing the exfoliation, so a scrub on top is too much.

If you are already using several actives, your TeleTest clinician can map them into a weekly schedule.

Realistic timing with consistent use:

• A few days to 2 weeks: blackheads start to clear; skin feels less greasy.
• 4 to 6 weeks: noticeable reduction in active acne and texture.
• 8 to 12 weeks: dark marks left from past acne begin to fade.

If after 8 to 12 weeks of consistent use there is no improvement, it is reasonable to revisit the plan with your TeleTest clinician.

Most are mild and settle within the first two to four weeks:

• Mild dryness or flaking
• Tingling or stinging for a few minutes after applying
• Slight redness around treated areas
• Temporary tightness

To reduce these: use less often, lower the strength, or apply a gentle moisturizer before and after.

Stop using your BHA and contact your TeleTest clinician if you notice:

• Burning that does not settle within an hour
• Blistering or raw skin
• New rash, hives, or facial swelling
• Worsening acne past the first six weeks (an initial "purge" in the first few weeks is common and usually settles)

Aspirin-family allergy: If you are allergic to aspirin or other related medications, do not use a BHA without checking with a clinician.

Low-strength topical BHA (around 2 percent or less) used on a small area is generally considered low-risk in pregnancy. Higher-strength leave-on products and in-clinic BHA peels are typically avoided. Always run any active skincare past your prenatal care provider and your TeleTest clinician before continuing during pregnancy.

BHA does not significantly increase sun sensitivity (unlike AHAs). Daily broad-spectrum sunscreen is still recommended though, because exfoliated skin is more vulnerable to UV damage and dark marks.

• Cleansers rinse off after a short contact time. They give gentle, daily exfoliation.
• Toners are applied to clean skin and left on. They give more exfoliation than a cleanser.
• Leave-on serums or lotions are applied to clean skin and left on. They give the strongest at-home effect.

Start with a cleanser if you are new to BHA. Add a toner or leave-on if your skin tolerates it well after 2 to 4 weeks.

• Pick a BHA for acne, blackheads, and oily skin.
• Pick an AHA for dullness, fine lines, sun spots, and surface dark marks.
• For mixed concerns, you can use both on different nights - or pick a product that combines them at a lower strength.

Yes. BHA body sprays, lotions, and washes are useful for body acne (chest, back, shoulders), rough patches on the upper arms (keratosis pilaris), and bumps on the buttocks or thighs. Body skin is thicker, so it tolerates slightly higher strengths than the face.

Yes. Medicated shampoos containing BHA are useful for flaky scalp, mild dandruff, and oily scalp acne. Apply to wet scalp, leave on for 3 to 5 minutes, then rinse out. Use 2 to 3 times a week. For persistent or itchy flakes, talk to a clinician about whether you need an anti-fungal shampoo too.

Persistent stinging usually means the strength is too high or your skin barrier needs support. Drop to every other day, apply moisturizer first, and pair with a barrier-supporting cream (with ceramides or niacinamide). If stinging continues after two weeks at lower frequency, switch to a gentler product or pause acids.

Look for: fewer blackheads, oilier zones feeling less greasy by midday, skin that feels smoother, fewer new pimples. If you see no change after 8 to 12 weeks of consistent use, talk to your TeleTest clinician about adjusting the strength or switching to a different active.

Carefully. Both exfoliate and both can irritate. Most plans alternate - vitamin A product some nights, BHA on other nights, with a barrier night in between. Your TeleTest clinician can map out a weekly schedule.

BHA body washes and sprays are a good first step for mild-to-moderate back acne. Use a 2 percent BHA body wash daily in the shower; leave on for 30 to 60 seconds before rinsing. For more inflamed acne, talk to your TeleTest clinician about adding a prescription treatment.

BHA does not bleach hair. It can mildly bleach dark fabrics over time if a leave-on product transfers to clothing, so apply at night and let it dry before getting dressed or going to bed in good linens.

The main BHA used in skincare is related to aspirin (acetylsalicylic acid). If you have a true aspirin allergy, you should avoid BHA skincare unless cleared by a clinician. If you have only had stomach upset from aspirin (not a true allergic reaction), topical BHA is usually fine.

At-home BHA peels (10 to 30 percent) are intended for occasional use - once a week or every other week at most. In-clinic peels (30 percent and above) are usually done every 4 to 6 weeks as a series. Daily BHA products (0.5 to 2 percent) are different - those can be used daily.

Yes. Niacinamide is gentle and supports the skin barrier. Layering niacinamide over a BHA serum reduces irritation and is a common, well-tolerated combination.

Book in-person dermatology care for:

• Severe nodular or cystic acne, especially with scarring
• A skin lesion or growth that is changing in size, colour, or shape
• Suspected warts that are not responding to OTC BHA treatments
• A skin reaction with swelling, blistering, or signs of infection

TeleTest provides virtual cosmetic-dermatology care for common concerns. Anything that needs a physical exam, biopsy, drainage, or in-clinic procedure is handled in person.

BHA skincare is sold as a cosmetic and is not covered under your provincial health plan. Prices vary:

• Drugstore cleansers, toners, and spot treatments: budget-friendly.
• Pharmacy wart and callus removers (high-strength, spot-use only): inexpensive per use.
• Brand-name cosmetic serums: mid-to-high range.
• In-clinic peels: per-treatment cost.

A TeleTest consultation can help match the right product and strength to your skin type so you do not over-spend or under-treat.