Hello, Phentermine is not recommended to be taken if you are addicted to smoking weed. Phentermine acts on the CNS, it is a CNS stimulant. Smoking weed also causes energy rush. It is dangerous to smoke weed while you are on Phentermine. Doing so will put you in risk of developing high blood pressure, cardiac problems, CAD, extreme agitation, severe chest pain or other complicated side effects that may be life threatening. You are suggested to inform your treating doctor so that you may be prescribed some other medicine that may suit you better and help to control your weight. Do regular walking twice daily. Do exercises. Take home made boiled food or food made in olive oil to lose weight naturally. Avoid taking sugar, refined flour, cheese, full fat dairy products, hot, spicy, oily food, and red meat. Take well-cooked whole cereals, fruits, veggies, lean meat, eggs, take home made balanced diet. Connect with a detox center to successfully quit smoking weed. Detox centers will help you wean off smoking weed gradually so that the withdrawal symptoms can be managed comfortably. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician