HI, thanks for using healthcare magic It would start reducing the blood pressure within 1 to 3 days. The side effects may or may not occur.Most persons use with minimal to no problems. Possible side effects are : decreased potassium, increased blood sugar, low sodium, increased uric acid, nausea, cramping, gallstones, constipation, muscle pain, dizziness, headache As mentioned you may experience none or all of these, it varies from one person to the next but if you do have problems, then the medication can be changed. High blood pressure is silent so you would not have any symptoms of the high blood pressure but you would develop complications. It silently affects the heart, kidney, brain and blood vessels in the body , causing changes that are usually irreversible. I hope this helps