It is strongly recommended to avoid drinking alcohol while taking phentermine. Combining phentermine, a stimulant, with alcohol, a depressant, can lead to enhanced and potentially dangerous side effects such as dizziness, drowsiness, difficulty concentrating, increased heart rate, and impaired judgment. The combination can also increase cardiovascular risks, irritate the gastrointestinal system, and reduce the effectiveness of phentermine for weight loss. Health professionals generally advise waiting at least 12 hours between alcohol consumption and taking phentermine if alcohol is consumed at all. Consulting a healthcare provider for personalized advice is crucial.