The increasing adoption of wearable devices in everyday life offers new possibilities for health monitoring, including the detection of alcohol intoxication. This technology holds significant potential in preventing alcohol-related incidents, particularly in reducing the risk of drunk driving and enhancing workplace safety. Photoplethysmography (PPG), commonly used in wearable devices, presents a promising approach for detecting alcohol-induces physiological changes in a practical, non-intrusive and continuous manner. The goal of this thesis is to introduce a novel method for monitoring alcohol intoxication thorough PPG, with a particular focus on frequency domain analysis by monitoring changes in the signal, recognizing that these changes can vary across different individuals.