Low Dosage Retinol and L-Cystine Combination Improve Alopecia of the Diffuse Type Following Long-Term Oral Administration

In a study conducted in 1989, a combination therapy of retinol, L-cystine, and gelatin was tested for its effectiveness in treating diffuse hair loss. The pilot study involved 36 patients and showed significant improvements, including an 8.3% reduction in the telogen rate, an 11% increase in the anagen rate, and a 6.9% increase in hair density. A subsequent double-blind study with 47 patients confirmed these findings, with a 13.5% decrease in the telogen rate and an 8% improvement in the anagen rate, while the placebo group showed no improvement. The treatment also improved the percentage of dysplastic anagen hairs by 7.4%, compared to a 26% increase in the placebo group. No systemic side effects were observed, suggesting that this combination therapy could be beneficial for treating diffuse hair loss.