Hi, thanks for using healthcare magic Tri olvance is a combination antihypertensive medication, it contains olmesartan, amlopdipine and hydrochorothiazide. The olmesartan is in the same family of drugs as the telma that you were previously taking and the amlodipine is the same as the amlong . Some of the possible side side effects of the olmesartan are dizziness, nausea, diarrhoea, electrolyte abnormalities. These may or may not occur. The only difference would be the hydrochorothiazide which is a diuretic (medication that makes the body lose excess fluid). Excess volume is one of the possible reasons for uncontrolled blood pressure and the diuretic would help in this aspect. If your doctor suggests the change in medication, then you should consider taking them, you may want to speak to him/her regarding any concerns that you may have. I hope this helps