ACEI drugs are angiotensin-converting enzyme inhibitors, which reduce the release of aldosterone and may cause hyperkalemia due to the reduced release of aldosterone. Generally speaking, if the patient does not have renal insufficiency, the process of taking such drugs will not cause hyperkalemia, except for some patients who may have renal insufficiency and are prone to hyperkalemia. The main representative drugs of the ACEI class are Benadryl and Perindopril.