The precautions of hyaluronic acid injection for decollete include preoperative attention and postoperative care. 1. Pre-operative precautions: keep your face clean on the day of surgery, no make-up; women need to avoid menstruation; prohibit anticoagulant drugs, such as aspirin, etc. before surgery; check your physical condition before surgery, no serious organ diseases, no coagulant diseases, no diabetes and immune diseases; prohibit smoking and drinking before surgery; eat a light diet before surgery, and avoid spicy and stimulating food. 2. Postoperative care: avoid contacting the injection area within 12 hours after the operation; keep the injection site clean and dry; do not touch and press the injection site after the operation; try to avoid the injection area and the surrounding area to apply topical medicines and cosmetics; avoid frequent movement of the facial muscles, do not do too much facial expression. The precautions of hyaluronic acid injections for decollete lines, specific can consult the professional physician’s opinion.