Olvance-CT 20 Tablet is a combination of two medicines. It helps to control high blood pressure in different ways. If high blood pressure is not treated it can lead to heart attacks, strokes and kidney failure. You can take Olvance-CT 20 Tablet with or without food. The dose will depend on your condition and how you respond to the medicine. Try to take it at the same time each day. It is important to keep taking this medicine until your doctor tells you not to. It contains a diuretic (water pill) and will make you urinate more so, it is best to avoid taking this medicine within four hours of going to bed. Use this medicine regularly to get the most benefit from it even if you feel well. High blood pressure does not usually have symptoms and if you stop taking it your risk of heart attack or stroke may increase. The most common side effect is dizziness. Other side effects include feeling tired, nausea, diarrhea, headache, and decreased blood pressure. Frequent urination is not a side effect of this medicine. It is the purpose of chlorthalidone and helps control your blood pressure. You may experience other possible side effects, but most are rare. Make sure you read the leaflet that comes with your medicines and tell your doctor if you are bothered by side effects or they do not go away. It may be possible to adjust your dose or try a different medicine. This medicine is not recommended during pregnancy and you should ask your doctor before taking it if you have kidney or liver disease, heart trouble or diabetes. Drinking alcohol can further lower your blood pressure and may cause side effects.