I understand people split up the doses like that due to the side effects like fatigue. What If 100 mg is not relieving pain for the first & second dose, is the 2nd option even worth it? If a person takes 150 mg , it relieves pain than 1st option. 100 mg doesn't relieve pain at all when you take it. I see people take different doses due to their pain. I hear from others that their doctor prescribed 150 x2 times a day. Others tell me they took 100 x3 times a day. How do you know which dosage is right for pain?