Stretch Marks: From Red to White

Striae distensae are a form of dermal scarring associated with pregnancy, rapid adolescent growth, corticosteroid exposure, and other physiologic or pathologic states. Early lesions are red or purple because of increased capillaries and may itch or hurt. As they mature, the epidermis becomes thinner, capillaries recede, collagen decreases, and the lesions become white. Mature white striae may narrow or flatten but do not disappear spontaneously.

Prevention and Treatment

Commercial oils and moisturizers have limited evidence for prevention. Weight control, exercise, management of conditions that raise cortisol, and balanced nutrition are more widely accepted. Once striae form, topical agents and energy-based treatments may improve appearance and symptoms.

The 2024 Chinese guideline on laser-aesthetic conditions reports that physical energy technologies provide some of the strongest available results, although no method is curative. Non-ablative fractional lasers, especially 1550 and 1565 nm, can significantly improve striae.

Evidence for 1565 nm Non-Ablative Fractional Laser

In a study of 20 patients with pregnancy-related striae, lesions were treated at 40–45 mJ and 200 spots/cm², while the full affected area including surrounding normal skin received 50–55 mJ and 150 spots/cm². Three sessions were performed at six-week intervals, with erythema and wheal formation as endpoints.

Texture, laxity, elasticity, and color improved. Eleven patients showed marked improvement, eight improved, and one did not, for a 95% response rate. At 1.5 months, 90% were satisfied or very satisfied.

International studies also support the approach. Six months after three sessions, one prospective study reported a mean 31.7% reduction in atrophic lesion depth and a 68% improvement in quality of life. Another preliminary report found that 91.7% of patients had more than 50% improvement in lesion volume and 83.3% had more than 50% pigment improvement. A 2025 randomized trial likewise found 1565 nm NAFL promising for texture, volume, and color.

How 1565 nm Treatment Works

Fractional photothermolysis creates a matrix of microbeams and microscopic treatment zones approximately 1 mm deep. These controlled columns activate epidermal migration, collagen remodeling, and repair of damaged tissue.

Unlike ablative fractional lasers, 1565 nm treatment preserves the skin barrier. Mild redness and swelling usually resolve within one to two days, cleansing can generally resume the same day, and downtime is minimal.

Recommended Parameters

1. Two-pass method

First pass: treat only the striae at 40 mJ and 300 spots/cm². Second pass: cover the entire distribution area at 50 mJ and 150 spots/cm². Use an adjustable spot and repeat every eight weeks for 3–5 sessions.

2. Single-pass method

Scan the full area once at 35 mJ and 300 spots/cm². This approach is faster and produces a shorter erythema period.

Parameters should always be adjusted to the patient's skin and clinical response.

References

[1] Chinese Society of Plastic Surgery. Guidelines for Common Laser-Aesthetic Conditions (2024).

[2] Guertler A, et al. Evaluation of a non-ablative, fractional 1565 nm laser for striae distensae albae. J Eur Acad Dermatol Venereol. 2019;33(1):220–226.

[3] Tretti Clementoni M, Lavagno R. A novel 1565 nm non-ablative fractional device for stretch marks. J Cosmet Laser Ther. 2015;17(3):148–155.

[4] Qu H, et al. PLLA injections versus non-ablative 1565-nm fractional laser for striae distensae. J Cosmet Dermatol. 2025;24(7):e70338.

Foremed Legend

Foremed Legend develops advanced energy-based aesthetic medical devices, including picosecond lasers, long-pulsed lasers, IPL systems, photoacoustic skin imaging, and cold-air therapy.