Topical Retinoid for Keloid Scars: Formulation and Concentration
For keloid scars, use tretinoin 0.05% cream applied topically once daily for at least 12 weeks, as this is the only concentration and formulation with published clinical evidence demonstrating significant reduction in keloid size and weight. 1
Evidence-Based Concentration Selection
The available evidence specifically supports tretinoin 0.05% for keloid treatment, based on a clinical study where this concentration demonstrated statistically significant decreases in both keloid weight (p < 0.04) and size (p < 0.01) after 12 weeks of treatment in patients with keloids present for an average of 7 years. 1
- No clinical data exists comparing 0.01%, 0.05%, or 0.1% concentrations specifically for keloid treatment, making 0.05% the evidence-based choice by default. 1
- Higher concentrations (0.1%) are used for acne and may provide faster results for inflammatory lesions, but this has not been studied in keloid populations. 2
- The 0.05% concentration represents a balance between efficacy and tolerability, as higher concentrations increase irritation risk without proven additional benefit for keloids. 1, 2
Cream vs. Gel Formulation
Use cream formulation rather than gel for keloid treatment, as the published keloid study specifically used tretinoin cream, and cream vehicles provide better tolerability on thickened scar tissue. 1
- Cream formulations are generally less irritating than gels, which is particularly important for keloid tissue that may already be inflamed, itchy, or tender. 1, 3
- The occlusive nature of cream vehicles may enhance penetration through the thick collagen bundles characteristic of keloids. 4
- Gel formulations are preferred for acne due to their non-comedogenic properties, but this consideration is irrelevant for keloid treatment. 3
Mechanism Supporting Retinoid Use in Keloids
Tretinoin addresses keloid pathophysiology through multiple mechanisms:
- Reverses abnormal MMP-13 upregulation in keloid-derived fibroblasts, which may contribute to keloid expansion into surrounding normal skin. 5
- Suppresses the markedly elevated MMP-13 expression in keloid tissue (peak suppression at 12 hours), while having minimal effect on normal fibroblasts. 5
- May improve chronic inflammation associated with keloids through inactivation of the AP-1 pathway. 5
- Affects collagen metabolism, which is fundamentally dysregulated in keloid formation. 1
Treatment Protocol
Apply tretinoin 0.05% cream once daily to the keloid for a minimum of 12 weeks to achieve measurable reduction in keloid size and weight. 1
- Begin with nightly application to minimize irritation risk. 1
- Monitor for irritant contact dermatitis, which occurred in 2 of 11 patients (18%) in the clinical study and required treatment discontinuation. 1
- Measure response using serial photographs, tape measurements, or volume assessment techniques. 1
- Consider combining with other modalities such as silicone gel sheeting or intralesional corticosteroids for enhanced efficacy, as tretinoin alone showed comparable effectiveness to silicone gel in scar prevention. 6, 4
Critical Pitfalls to Avoid
- Do not use tretinoin gel formulations without evidence supporting their use in keloids, as the cream vehicle was specifically studied. 1
- Do not use concentrations other than 0.05% without recognizing this is extrapolation from acne data rather than keloid-specific evidence. 1, 2
- Do not expect rapid results—the study demonstrating efficacy required 12 weeks of continuous treatment. 1
- Counsel patients about irritation risk and the need to discontinue if severe contact dermatitis develops, as this affected nearly 1 in 5 patients. 1
- Recognize tretinoin is adjunctive therapy, not definitive treatment—keloids remain challenging to treat and often require multimodal approaches including intralesional steroids, surgery, or radiotherapy for optimal outcomes. 4