## 3 Results
### Side Effects of HIFU  
Recent studies report that redness is the most commonly observed side effect, typically resolving immediately after treatment. However, if the device head is not applied with sufficient pressure or if an inadequate intermediate material (gel) is used, skin surface irritation may occur. Although this reaction is reversible, it indicates improper treatment application. Possible causes include the following:  
* Insufficient contact between the device head and the skin;
* Inadequate amount of gel;
* Higher-than-recommended energy intensity.  
Additionally, if the operator fails to avoid non-permissible areas (e.g., temples, eye sockets, or the depressor anguli oris muscle) and applies HIFU in these regions, it may lead to temporary facial nerve paresis.  
During the procedure, patients commonly experience the following:  
* A sensation of increased temperature on the skin;
* Mild pain, which is generally well tolerated;
* Mild redness in the treated area, which disappears immediately after the procedure.  
Most studies have evaluated HIFU-related risks for up to 12 weeks post treatment. However, only one study has assessed safety and documented adverse events over a 24-week period [12].  
HIFU side effects include mild-to-moderate discomfort, bruising (ecchymosis), and swelling (edema), all of which are transient and resolve naturally. No reports exist of scarring, burns, or clinically significant changes in lipid panels, inflammatory markers,  
\begin{table}
\begin{tabular}{c p{142.3 pt}} \hline \hline
**Category** & **Requirements** \\ \hline Personal History & The patient should not belong to any contraindicated categories. \\ \hline Professional Expertise & Adequate knowledge and experience in the use of HIFU devices for facial and body esthetic procedures. \\ \hline Diagnosis & Accurate diagnosis of the case and discussion with the patient to ensure they have realistic expectations and understand the expected results. \\ \hline Device & The HIFU device should be reliable, properly maintained, and correctly adjusted according to the protocol for each device. The selection of the appropriate headpiece should consider factors such as skin type, hydration levels, age, and the specific esthetic concern. \\ \hline Application & Proper pressure of the handpiece on the skin, sufficient use of ultrasound gel, and avoidance of non-permissible areas (temples, eye sockets, and the levator labii superiotis (LLS) muscle) must be ensured. Avoid applying HIFU multiple times to the same spot. Follow appropriate time intervals between sessions (e.g., a second HIFU treatment using the 3 mm headpiece may be performed three months after the first treatment). \\ \hline Patient Instructions & Clear pre- and post-treatment guidelines should be provided. \\ \hline Patient Cooperation & The patient must follow all pre- and post-treatment instructions to maximize results and minimize risks. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Basic prerequisite for safe and effective HIFU application. (Modified by Dr. [PERSON], 2025).  
renal function, or liver function [13]. Furthermore, no study has linked HIFU to any serious or permanent adverse effects [4].  
However, when HIFU is performed correctly and all safety conditions are met, the likelihood of side effects or complications is minimal. The following table summarizes the most common complications and side effects associated with HIFU in esthetic procedures: (Table 2).