Avapro - Can I take 1/2 my dose of irbesartan? I take 75 mg. Feel tired and dizzy?

No you can't take half of what the dr ordered for your blood pressure. If you have side effects then you need to see your dr and get something else ordered. The only way you'd be able to tell if it was really too strong would be if your blood pressure bottomed out. What you are experiencing is side effects not related to it being too strong.