Following weight loss with GLP-1 receptor agonists, facial skin laxity and sagging have become another concern for some patients. The temples, cheeks, tear troughs, jawline, marionette lines, and nasolabial folds are the most common areas of volume loss or wrinkles after semaglutide treatment. Restoring facial volume after discontinuing weight-loss medications poses a challenge, as the sole use of hyaluronic acid or permanent fillers may lead to a significant number of patients requiring corrective treatment for overfilled facial syndrome.Poly-L-lactic acid (PLLA) works by releasing low concentrations of lactic acid to stimulate fibroblast-mediated collagen synthesis. Additionally, macrophages participate in the collagen production process triggered by lactic acid, ultimately improving skin laxity. This study aims to evaluate the safety and efficacy of PLLA injections in addressing facial laxity following GLP-1 analogue therapy.

Inclusion Criteria:

1. Adults who have received GLP-1 analog therapy and experienced significant weight loss (BMI reduction ≥ 5%).
2. Aged 30 to 60 years, with noticeable facial sagging, and nasolabial folds or marionette lines rated 2 to 4 on the Wrinkle Severity Rating Scale (WSRS).
3. Subjects who have fully understood the clinical trial protocol and associated risks, voluntarily signed the informed consent form, and expressed willingness to undergo facial injection treatment.

Exclusion Criteria:

1. Known or previous allergy or hypersensitivity to any component of the product.
2. Known or previous allergy to local anesthetics (e.g., lidocaine or other amide-type anesthetics).
3. History of severe or multiple allergies, such as severe systemic anaphylactic reactions.
4. Previous surgery (including cosmetic surgical procedures or liposuction), piercings, or tattoos in the area to be treated.
5. Prior tissue filler treatments or contouring in the area to be treated, including the use of any permanent fillers, or any semi-permanent fillers, autologous fat, lifting threads, or permanent implants within 24 months before treatment.
6. Use of any biodegradable facial tissue fillers based on hyaluronic acid or collagen in the area to be treated within 12 months before treatment.
7. Botulinum toxin injections in the area to be treated within 6 months before treatment.
8. Presence of any disease or lesion in or near the area to be treated, such as inflammation, active or chronic infection (e.g., in the oral, head, and neck regions); facial psoriasis, eczema, acne, rosacea, perioral dermatitis, herpes simplex, or herpes zoster; scars or deformities; cancer or precancerous lesions (e.g., actinic keratosis).
9. Past or current active collagen diseases, e.g., systemic lupus erythematosus, rheumatoid arthritis, polymyositis, dermatomyositis, or localized or systemic scleroderma.
10. Predisposition to keloid formation, hypertrophic scarring, or any other abnormal healing.
11. History of bleeding disorders or, in the investigator's judgment, treatment with thrombolytics, anticoagulants, or platelet aggregation inhibitors within a relevant period before treatment.
12. Treatment with chemotherapy, immunosuppressants, immunomodulatory therapies (e.g., monoclonal antibodies), or systemic corticosteroids (inhaled corticosteroids are permitted) within 3 months before treatment.
13. Treatment with topical (below the infraorbital rim) retinoids or corticosteroids within 1 month before treatment, or systemic retinoids within 6 months before treatment.
14. Any medical condition that, in the investigator's opinion, makes the subject unsuitable for inclusion.
15. Other conditions that, in the investigator's opinion, preclude the subject from participating in the study, e.g., subjects who may be unable to avoid other facial cosmetic treatments, subjects deemed potentially unreliable, unreachable, unable to understand study assessments, or with unrealistic expectations regarding treatment outcomes.
16. Pregnant or breastfeeding women, women of childbearing potential not using adequate contraception, or women planning pregnancy during the study period.
17. Subjects planning to undergo any other facial plastic surgery or cosmetic procedures (e.g., laser or chemical peels, microneedling, facelifts, radiofrequency treatments, etc.) below the infraorbital rim during the entire study period.
18. Moderate to severe asymmetry in the midface assessment, i.e., a difference of more than 1 grade in the WSRS ratings between the two sides of the face.
19. Intentional significant weight change (BMI change ≥ 2) during the study period.