Minor side effects include insomnia, dizziness, anxiety, palpitations, tachycardia, nausea, vomiting. Major side effects include convulsions, chest pain, hypertension, shortness of breath, and cardiac dysrhythmias. These drugs were already known to increase risk of primary pulmonary hypertension, a potentially life-threatening condition with shortness of breath, fatigue, and dizziness as symptoms. Following the withdrawal of fenfluramine from the market, some dieters are trying combinations of phentermine with prescription antidepressants such as Prozac. These antidepressants have not been adequately tested and are not approved by the FDA for weight loss purposes.
Most people regain the lost weight once the medications are stopped.
Because obesity is a chronic condition, long term use of medication may be indicated. Your doctor may feel your health could benefit from using medications for longer periods of time or in combination depending on how the medications are working and whether or not you are experiencing side effects. The potential for serious side effects makes prescription medications for obesity unsafe for cosmetic weight loss.