The medicine is usually well tolerated, but dizziness, headaches, insomnia, nervousness, dry mouth, taste disorders, vomiting, constipation, or diarrhea may occur. In addition, there may be pain in the chest, sexual dysfunction, urination disorders and rare skin rashes. If you take more than 3 months, you can experience heart disease and addiction. Phentermine contains soybean oil. If you are allergic to peanuts or soy, do not take this medicine. If any undesirable effects or other unusual reactions occur, talk with your doctor about your next use.