Medication dosage question

Patient: My doctor prescribed me phentermine 37.5 mg tablets to be taken once daily for weight loss, today is day 4 and I continue to feel very jittery and shaky. Is it ok to break the tab in half and take half first thing in the morning and the other half a few hours later?

Symptoms: Jittery/shaky/increased resting heart rate

Doctor: Hello. Welcome to Ask The Doctor.Yes, phenteramine causes these side effects. This drug is poorly tolerable.Yes. Y ou can break the tablet and start with half the dose and increase it gradually.I would advise you to take it in the night.In case you continue to get the side effects even at this dose, you should report your doctor.Also important is to exercise. Pill alone is not going to help you best.I would also advise you to discuss with your doctor about Orlistat.That is relatively a safer drug for weight loss and with tolerable side effects.I hope it helps.Good Luck.