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. Alpha blockers lower blood pressure by preventing the body's nervous system from stimulating the muscles in the walls of the smaller arteries. Therefore, the muscles don't narrow or constrict as much. Also, alpha blockers reduce the effects of the hormones norepinephrine and epinephrine which narrow blood vessels. They also lower total blood cholesterol and triglyceride levels.