AHA BHA Protocol for Post-Inflammatory Erythema (PIE): Optimizing Red Mark Recovery After Acne

A targeted exfoliation routine that soothes inflammation and restores clear, even skin tone.

By Sneha Tete, Integrated MA, Certified Relationship Coach

Created on Oct 8, 2025

A targeted exfoliation routine that soothes inflammation and restores clear, even skin tone.

Persistent red marks after acne, medically termed post-inflammatory erythema (PIE), can be emotionally distressing and cosmetically challenging. Advanced protocols leveraging Alpha Hydroxy Acids (AHA) and Beta Hydroxy Acids (BHA) now provide practical, science-driven strategies for addressing PIE, improving skin texture, and restoring clarity. This comprehensive guide explains PIE, the AHA-BHA mechanism, evidence for efficacy, protocols, safety, and answers key questions about treatment optimization and risk minimization.

What is Post-Inflammatory Erythema (PIE)?
Understanding Alpha Hydroxy Acids (AHA) and Beta Hydroxy Acids (BHA)
PIE Marks and Their Resolution
How AHA and BHA Address PIE: Mechanisms and Evidence
Stepwise AHA BHA Protocol for PIE
Product Selection: Key Ingredients and Formulations
Supportive Care and Sun Protection
Clinical Considerations and Safety
Frequently Asked Questions (FAQs)
References

If you're looking for effective methods to tackle post-inflammatory erythema, our guide on comprehensive approaches to treating PIE red marks offers valuable insights and strategies that can significantly enhance your understanding and management of this condition.

What is Post-Inflammatory Erythema (PIE)?

Post-inflammatory erythema (PIE) refers to flat, red-to-pink discolorations that commonly occur after inflammatory acne—often persisting for weeks or months after active lesions subside.
Key characteristics of PIE:

Flat, pink to red spots (not raised or indurated)
Occur after inflammatory acne (papules, pustules, cysts)
Result from dilated capillaries and residual skin inflammation
Different from post-inflammatory hyperpigmentation (PIH), which is brown
More visible in lighter skin phototypes, but can affect any skin

For a deeper understanding of how to differentiate between various skin discolorations caused by acne, check out our comprehensive guide on PIE vs PIH treatment for teens, which outlines tailored approaches for both conditions.

Why does PIE take so long to fade?
PIE is due to increased blood flow and fragile new skin following inflammation. Unlike pigment changes in PIH, PIE is vascular; natural resolution can take several months without intervention.
Triggers that slow healing include UV exposure, picking/scratching, and improper skincare.

Understanding Alpha Hydroxy Acids (AHA) and Beta Hydroxy Acids (BHA)

AHA and BHA are both chemical exfoliants but with distinct properties and effects on skin:

Property	AHA (e.g., Glycolic Acid, Lactic Acid)	BHA (e.g., Salicylic Acid)
Chemical Nature	Water-soluble acids from fruit or milk	Lipid-soluble, derived from willow bark
Primary Action	Exfoliate superficial (surface) skin layers; improve cell turnover	Penetrate into oil-laden pores; exfoliate inside follicle
Secondary Actions	Enhance hydration, boost collagen, even skin tone	Anti-inflammatory, antimicrobial, regulate sebum
Typical Uses	PIE, PIH, melasma, textural irregularities	Oily/acne-prone skin, comedones, inflammatory lesions, PIE
Sensitivity/Tolerance	Can cause mild redness, tingling, transient dryness	Generally well-tolerated; rare irritation

To fully harness the benefits of chemical exfoliation in your skincare routine, don't miss our article on tackling post-inflammatory hyperpigmentation with weekly peels. It presents essential tips for safely incorporating acids into your regimen.

Common Types Used for PIE

Glycolic Acid (AHA): Highly effective, available in 5–70% formulations. Good evidence for pigmentation and texture.
Lactic Acid (AHA): Milder than glycolic acid. Suitable for sensitive or drier skin types.
Salicylic Acid (BHA): Typically 0.5–2% in OTC products; up to 30% in professional peels.
Excellent for inflamed and oily skin, deep cleansing of follicles.

PIE Marks and Their Resolution

Pathogenesis: PIE occurs due to fragile, dilated blood vessels (capillaries) in the healing dermis, left behind after the inflammatory phase of acne. The redness persists even after active acne resolves and is often exacerbated by trauma (picking) and sun exposure.

Considering options for professional-grade results? Explore our insights on finding the best acid for hyperpigmentation treatment through chemical peels, ensuring you're informed on how to achieve optimal skin clarity.

Natural course: Red marks can persist for several months or even longer, especially in individuals with sensitive skin or ongoing inflammation.

Clinical importance: While harmless, PIE can significantly impact self-esteem and motivation to pursue treatments for acne and its after-effects.

How AHA and BHA Address PIE: Mechanisms and Evidence

AHAs and BHAs accelerate resolution of PIE by the following mechanisms:

Increased cell turnover: Both AHA and BHA promote desquamation and stimulate the basal layer, replacing damaged and inflamed skin cells with healthy ones more rapidly.
Reduction in capillary dilation: Gentle, repeated chemical exfoliation diminishes superficial vascular congestion and speeds normalization of the skin barrier.
Anti-inflammatory action: BHA in particular (salicylic acid) has strong anti-inflammatory effects, reducing redness and soothing irritation during and after acne flares.
Improved skin texture and tone: AHAs, like glycolic acid, help fade residual pigmentary or textural irregularities that often accompany PIE.
Sebum regulation: BHAs help maintain clear pores, which may reduce further acne and new PIE formation.

Research Backing:

A clinical study on glycolic acid (AHA) and salicylic acid (BHA) peels found that both modalities significantly improved post-acne pigmentation and red marks. Glycolic acid (GA) led to over 75% reduction in pigmentation/erythema in 45% of patients over six weeks, compared to none in the BHA (SA) group achieving that threshold.
Both treatments provided significant benefit, with GA showing a higher percentage improvement overall.
Salicylic acid is especially useful in reducing redness and inflammation due to its anti-inflammatory and keratolytic properties.
In clinical protocols, use of chemical peels with either glycolic acid or salicylic acid has been shown to be effective in expediting recovery from PIE and minimizing persistent redness.

Stepwise AHA BHA Protocol for PIE

A carefully structured routine, tailored to skin sensitivity and PIE severity, maximizes results while limiting side effects.

1. Prepare the Skin

Cleanse gently with a non-stripping, fragrance-free cleanser.
Ensure skin is free of makeup, oil, and sunscreen residue.
Wait until skin is dry before applying actives to minimize irritation.

2. Initiate AHA and/or BHA Application (Home Use)

Frequency: Start 2–3 times per week. Gradually increase to daily or alternate-day use as tolerated.
Layering: Some can layer AHA (morning or evening) and BHA (alternate day or opposite routine) as tolerated; avoid layering both at high concentrations until skin builds tolerance.
Product form:
- AHA: Serums (e.g., 5–10% glycolic or lactic acid), lotions.
- BHA: 1–2% salicylic acid solutions, gels, or toners.

3. Professional Chemical Peels for PIE (In-Clinic)

Dermatologists may use higher concentrations for rapid improvement—typically 20–50% glycolic acid or 20–30% salicylic acid—spaced 2–4 weeks apart.
Sessions involve skin prep, eye protection, timed peel application, rinsing, followed by application of cooling compresses and sunscreen.
Patients should avoid sun, abrasion, and other cosmetic procedures during the treatment period and healing phase.

4. Aftercare

Moisturize with a bland, barrier-repairing cream (ceramides, glycerin, or petrolatum-based).
Avoid actives (retinoids, vitamin C, strong AHA/BHA) for 24–48 hours post-peel.
Daily, broad-spectrum sunscreen (SPF 30+), reapplied every 2 hours when outdoors, is non-negotiable.
Monitor for excessive redness, blistering, or pain, and contact a provider if severe symptoms develop.

Product Selection: Key Ingredients and Formulations

Selecting the right product is essential for efficacy and lowering risk of irritation, especially for those new to acids or with sensitive skin.

Recommended Ingredients

Glycolic acid (5–10%): Effective for textural refinement and PIE fading. Start with lowest concentrations if skin is sensitive.
Lactic acid (5–8%): Alternative AHA for drier or more sensitive skin. Provides gentle exfoliation, mild lightening.
Salicylic acid (1–2%): Gold standard BHA for red marks and prevention of new breakouts.
Supporting actives: Niacinamide (anti-inflammatory, strengthens barrier), hyaluronic acid (hydration), and panthenol (soothing).

Formulation Tips

Avoid combined formulas with high concentrations of both AHA and BHA for home use to minimize irritation.
Patch test new products prior to wide application—wait 24–48 hours between first use and reassess for reaction.
Check product labels for pH (optimum: 3.5–4.0 for efficacy but tolerability for regular use), stability, and irritant-free bases.

Supportive Care and Sun Protection

Optimizing outcomes goes beyond just acids. Supportive strategies speed recovery and minimize additional damage:

Sunscreen: Mandatory. UV exacerbates erythema and delays healing; photo-protection is critical. Choose oil-free, non-comedogenic formulas suited for acne-prone skin.
Antioxidants: Vitamin C, vitamin E, and niacinamide reduce oxidative stress, support healing, and complement acid protocols.
Topical retinoids: When tolerated, help normalize skin turnover and fade residual marks. Start at low frequency to avoid aggravation.
Barrier repair: Defend against over-exfoliation by using emollients, ceramide creams, and gentle cleansers.
Avoid picking or scratching: Trauma delays fading and increases risk of scarring or pigmentation.
In-office therapies: For persistent PIE, consider vascular lasers (e.g., pulsed dye laser), microneedling, or IPL, under expert supervision.

Clinical Considerations and Safety

Side Effect Profile:

AHAs: Possible transient stinging, redness, dryness, mild peeling; generally mild at low concentrations. Titrate to avoid overuse.
BHAs: Well tolerated; occasional peeling or tingling at higher concentrations. Rare allergic reactions reported.
Cautions: Overuse or excessive concentration increases risk of skin barrier damage, longer-lasting erythema, or paradoxical post-inflammatory hyperpigmentation (PIH) in darker skin types.

Who Should Be Cautious?

Persons with known sensitivities to acids or aspirin (salicylate allergy, for BHA)
People with active eczema, extremely sensitive, or broken skin
Pregnancy (consult physician about safety; most topical BHAs and lower-strength AHAs considered low risk in moderation)

When to Seek Professional Advice: If PIE persists after several months of proper at-home protocols, or if you experience significant irritation, blistering, or signs of infection, consult a dermatologist.

Frequently Asked Questions (FAQs)

Q: Is it safe to use both AHA and BHA together on the same day?

A: It can be safe for tolerant, non-sensitive skin to alternate or layer AHA and BHA, but most experts recommend starting with just one class, then slowly introducing the second. Avoid mixing high-concentration peels at home.

Q: How long does it take to see results with AHA/BHA for PIE?

A: Improvement can be observed within 4–8 weeks, but optimal fading of PIE may require 12–16 weeks or longer, especially if marks are longstanding.

Q: Should I stop other acne medications while using AHA/BHA?

A: Consult your dermatologist, but many topical acne therapies (e.g., benzoyl peroxide, retinoids) can be continued with careful spacing and skin monitoring to avoid irritation.

Q: Is chemical peeling for PIE safe for darker skin?

A: Both AHA and BHA can be used safely when applied by experienced professionals, but TCA and higher strengths pose greater risks for PIH. Mandelic acid (AHA) and salicylic acid (BHA) are preferred for Fitzpatrick IV–VI skin types.

Q: Are there any long-term risks with regular AHA/BHA use?

A: When used as directed, long-term risks are minimal. Chronic overuse without adequate barrier repair or sun avoidance can sensitize the skin.

References

Efficacy of Alpha and Beta Hydroxy Acid Chemical Peels in the Treatment of Postacne Pigmentation and Erythema
Best Chemical Peels for Acne: AHA vs BHA vs TCA 2025
SLMD Skincare: Post-Inflammatory Erythema: Treating After-Acne Red Spots
Paula’s Choice: Post-Acne Marks: Causes, Types + Treatments
Medical News Today: Understanding AHA and BHA for Skin Care

References

Author

Sneha TeteBeauty & Lifestyle Writer

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to thebridalbox, crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

Read full bio of Sneha Tete