Switching from Olmezest H (with hydrochlorothiazide) to Olmezest CH (with chlorthalidone) is a common step because chlorthalidone is a stronger, longer-acting diuretic. However, it can take 2 to 4 weeks for this new medication to show its full blood-pressure-lowering effect. Your body is likely still adjusting. What you should do next: 1. Continue taking it: Do not stop or change your dose without consulting your doctor. 2. Monitor daily: Record your blood pressure twice daily (morning and evening) for a week. 3. Limit salt: High sodium intake can hinder the drug's effectiveness. 4. Follow up: Share your BP log with your doctor in a week to see if further adjustment is needed.