###### Abstract  
High-intensity focused ultrasound (HIFU) is a non-invasive technology widely used for facial and body rejuvenation, skin tightening, and fat reduction. It stimulates collagen production and induces apoptosis in fat cells, offering an effective alternative to surgical procedures with minimal downtime and reduced recovery periods. As a result, HIFU has become an increasingly popular choice for patients seeking non-surgical esthetic enhancements. A comprehensive literature search was conducted using PubMed, Scopus, and SpringerLink to assess HIFU-related complications. Twenty-two studies published between 2010 and 2025 were identified, all involving female participants. The findings confirm that HIFU is generally safe and effective, with most complications being mild and transient, such as temporary erythema, swelling, and discomfort. These side effects typically resolve within a few hours to days without requiring medical intervention. However, rare but significant complications like fat atrophy, nerve irritation, and hyperpigmentation have been linked to improper device settings, inadequate practitioner expertise, and insufficient patient assessment. Ensuring proper training, adherence to standardized treatment protocols, and individualized patient evaluations can significantly minimize these risks and optimize patient outcomes. Long-term follow-up studies and further research on standardized safety protocols, optimal energy settings, and patient selection criteria are essential for enhancing the effectiveness, predictability, and safety of HIFU in esthetic medicine. H  
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removal of neoplasms, with little to no effect on the surrounding tissue. The oldest and most popular clinical application of HIFU is the removal of prostate cancer. It is also used for uterine fibroids and the removal of bone metastases, as well as in other organs. One of the most recent HIFU applications is tattoo removal [1; 2]. HIFU is used as an esthetic procedure and is a contemporary, non-invasive treatment technique that has been proven to effectively minimize fat accumulation while simultaneously improving skin laxity [2]. The most important non-thermal mechanism of tissue disruption using HIFU is acoustic cavitation, which causes local destruction of the targeted tissues due to the high pressures and temperatures caused by cavitation. The fundamental operating principle of this technology is the conversion of mechanical energy into thermal energy. The energy that is generated at specific focal points within the tissue can induce the denaturation of tissue components, such as collagen. This process leads to tissue remodeling and assists in restoring the structural integrity of the treated areas [3]. Studies have demonstrated that ultrasound can be selectively and deeply absorbed by tissues, in a controlled manner, making it highly efficient for esthetic problems [4]. The headpieces of HIFU are specialized and are applied directly to the surface of the skin using a conductive ultrasound gel. The gel ensures optimal transmission of ultrasound waves to the appropriate depth for effective treatment. These headpieces are equipped with probes that can penetrate different depths within the skin, including 1.5 mm, 3 mm, 4.5 mm, 6 mm, 8 mm, 13 mm, and 16 mm. HIFU treatment has the advantage of penetrating deeper into tissues than other non-invasive technologies used for esthetic procedures [1]. Despite penetrating so deeply, the procedure is non-invasive because it does not cause any injury or irritation to the epidermis [5]. The main mechanism of HIFU is to convert acoustic (mechanical) energy into thermal energy and, as a result, to create biological effects in the dermis, superficial myoaneurotic system (SMAS), and fat tissue. Focusing high-energy ultrasound causes a temperature increase of 65-75 \({}^{\circ}\)C at microscopic points in different layers of the skin, depending on the target tissue and the esthetic problem. When the temperature in the dermis is above 42\({}^{\circ}\), the fibroblasts begin to produce collagen.