Why does the skin feel warm after applying formic acid 1.4%? — SIPELGHACI 1.4% 50ML (Самарамедпром, Россия)

A feeling of warmth is the intended cosmetic response to this product. Formic acid at 1.4% is a low concentration that nevertheless gently irritates the very surface of the skin. This mild irritation encourages local microcirculation—blood flow in the small vessels near the surface—so the area may feel warmer and more alive for a while after application. This is why the product is described as a rubefacient.

Use only a small amount on a limited area to get this effect. The warming feeling is temporary. If you feel strong burning, pain, or any reaction that worries you, stop using the product and rinse the area with water. Do not apply it to broken, irritated, or very sensitive skin, and keep it away from eyes and mucous membranes.

This cosmetic effect is not a treatment for any medical condition. The product is not intended to diagnose, treat, or prevent any disease. If you have questions about your skin or a medical condition, ask a doctor or pharmacist.