Hello, Both Coversyl and Zircol are antihypertensives which act in a different manner to control blood pressure. The addition of Zircol adds up to lowering your blood pressure together with Coversyl. They don t usually have any drug interaction as they are usually used as combination for hypertension which is not or is partially responsive to a singe medication. I recommend frequent follow-ups for dose adjustments, together with low salt and fat diet, as well as a regular exercise routine for better blood pressure control. Hope I have answered your query. Let me know if I can assist you further. Take care Regards, Dr Daryl Derick B. Dizon, General & Family Physician