Onion extract is an active ingredient extracted from the bulb of the onion, family Liliaceae, with anti-inflammatory, antibacterial and fibrinolytic properties. It is the main active ingredient in compounded sodium heparin allantoin gel scar treatment, which consists mainly of onion extract, sodium heparin and allantoin. It is suitable for the treatment of hypertrophic keloid and keloid scars, secondary to the scarring produced after surgery, amputation, burns, acne and other accidents that restrict movement and affect aesthetics, etc.