Legal vs. illegal injectable fillers: The adverse effects comparison study
Related Experiment Video
Updated: Dec 21, 2025

The Quantification of Injectability by Mechanical Testing
Published on: May 13, 2020
Onjuta Chayangsu1, Rungsima Wanitphakdeedecha1, Penvadee Pattanaprichakul1
1Department of Dermatology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Background:
Over the past decades, soft-tissue filler injections have become an essential part of cosmetic practice worldwide. Due to the increasing demand, unlicensed practitioners venture in performing this minimally invasive procedure, injecting illegal fillers that pose serious complications.
Objectives:
To compare the adverse effects of legal and illegal soft-tissue fillers injected by licensed and unlicensed practitioners.
Materials And Methods:
A 10-year retrospective, descriptive, single-center study conducted at the outpatient dermatology department and skin laser center at Siriraj Hospital from January 2009 to December 2019. Patients were identified as having treatment-related complications. Their demographic data, clinical history, and injection history were reviewed.
Results:
Forty patients with mean age of 37 years old were included in the study. Thirty-five of them (87.5%) were female. Illegal soft-tissue fillers were used in 28 patients (70%) and were performed by unlicensed practitioners (18 cases, 64.3%, P = .001). Adverse effects from illegal fillers (26 cases, 92.9%) developed longer than legal fillers (7 cases, 58.3%) (P = .017). Symptoms significantly lasted longer in patients injected with illegal fillers, 10 (0.07-288) weeks, as compared to patients injected with legal fillers 0.75 (0.14-72) weeks (P = .01). Injections from illegal fillers resulted to foreign body reaction (22 cases, 78.6%) and infections (6 cases, 21.4%). Vascular complications were identified in legal fillers injections (5 cases, 41.7%).
Conclusions:
The incidence of adverse effects and complications from soft-tissue filler injections are superior when performed by novice injectors and unlicensed practitioners using illegal fillers. Proper training of filler injections, selection of appropriate fillers, and early recognition of adverse effects are critically important to the success of treatments.
Related Concept Videos
Local Anesthetics: Adverse Effects
Once absorbed into the systemic circulation, local anesthetics can affect the organs that depend on the functioning of sodium...
Pharmaceutical Alternatives: Stability-Related Therapeutic Nonequivalence
Pharmaceutical Alternatives: Excipients and Impurities-Related Therapeutic Nonequivalence
Local Anesthetics: Clinical Application as Epidural Anesthesia
Since epidural anesthetics can be infused through an epidural catheter, all types of drugs, including short-acting ones, can be administered. Chloroprocaine and lidocaine are examples of short and long-duration anesthetics, respectively. Bupivacaine...
Local Anesthetics: Pharmacokinetics
Bioequivalence studies: Biowaivers

