When angiotensin I turns into angiotensin II, it constricts the blood vessels, increasing blood pressure. About 20 percent of people who take ACE inhibitors develop a dry cough. Angiotensin II receptor blockers block the action of angiotensin II and do not increase bradykinin. Side effects are uncommon. However, some individuals who take these drugs may experience dizziness, nasal congestion, back and leg pain, diarrhea, indigestion and insomnia.
Calcium antagonists work by affecting the muscle cells around the arteries.
These muscle cells have tiny passages in their membranes called calcium channels. When calcium flows into them, the muscle cells contract and the arteries narrow. Calcium antagonists fill these channels and prevent calcium from getting into your muscle cells. Some calcium antagonists slow the heart rate, potentially reducing blood pressure. Side effects may include constipation, headache, rapid heartbeat, rash, swelling in feet and lower legs and swelling of gums.