8 Classes of Blood Pressure Drugs and Why Are They 3rd on the 10 Most Dangerous Drugs List
When you go to the doctor and you’re told you have high blood pressure, you probably aren’t told to go home and change your diet but indeed, that should be the first thing you do as well as addressing other aspects of lifestyle. Here are 8 classes of blood pressure drugs.
Medications that lower blood pressure do come with a price and side effects. Many of the side effects such as dizziness, the need to urinate more frequently, or impaired thinking may increase the risk of falls in the elderly. Other side effects such as higher blood sugar can cause issues for people with diabetes. In men, impotence is a big issue.
1. Ace Inhibitors (Angiotensin-converting enzyme) - inhibitors prevent your body from making Angiotensin II, a natural substance our bodies produce that among other things, can cause our blood vessels to narrow, thicken and stiffen. Angiotensin II also triggers the release of a hormone associated with increased water and sodium in the body.
Side effects: Most common - Dry cough. Less common – light headedness, dizziness, rash, reduced appetite, increased blood potassium level, changes in the flavor of food and swelling. ACE inhibitors are associated with birth defects. Some pain relievers reduce the effectiveness of ACE inhibitors.
2. Alpha Blockers - stop the hormone norepinephrine (noradrenaline) from constricting the muscles that surround the veins, smaller arteries, and other muscles throughout the body.
Side effects: Include “first dose effect” – when first taking Alpha Blockers, some people get dramatically reduced blood pressure, dizziness, and feel faint when sitting or standing up. Additional side effects include headache, pounding heartbeat, nausea, weakness, and weight gain.
3. Angiotensin II Receptor Blockers - block the action (not the production) of Angiotensin II.
Side effects: Diarrhea, dizziness, headache, light-headedness, back and leg pain, sinus congestion, kidney failure, liver failure, allergic reaction, lowered white blood cells, swelling and is also associated with birth defects. ARB’s are linked to some types of cancer including lung cancer. (See Cancer Risk below)
4. Beta Blockers (Beta adrenergic blocking agents) - block adranaline (epinephrine) causing the heart to slow and blood vessels to open.
Side effects: Cold hands, dizziness, fatigue, weakness, depression, reduced libido, insomnia, shortness of breath, severe asthma attacks, may block signs of low blood sugar in diabetics (like racing pulse), and can affect cholesterol and triglyceride levels. Stopping the drug abruptly may lead to increased risk of heart attack. Some physicians see a link between Beta Blockers and INCREASED heart disease.
5. Calcium Channel Blockers (calcium antagonists) - Inhibit calcium ions from getting into the cell walls of the heart and the muscles surrounding blood vessels, causing them to relax (for a muscle to contract, it needs calcium ions Ca2+ to cross its cell membrane).
Side effects: Constipation, drowsiness, flushing, headache, nausea, and swelling of the lower legs and feet. Some calcium channel blockers react with grapefruit and foods that contain grapefruit by blocking the liver from properly removing them from the blood – resulting in dangerous concentrations. Not only are the short-acting calcium channel blockers been linked with cancer, but they have been shown to increase risk of death from a heart attack, says the National Institutes of Health, which also says they should be prescribed with caution.  In addition, this class of drugs has been linked to 50% increase in breast cancer. 
6. Central Acting Agents (also called central adrenergic inhibitors; central alpha agonists; central agonists) – These drugs work directly in the brain, blocking signals that speed up the heart rate or constrict blood vessels, This class of drugs is less commonly prescribed due to strong side effects.
Side effects: Constipation, depression, drowsiness, dizziness, dry mouth, fatigue, impotence, headache, impaired thinking and weight gain. Abrupt discontinuation can cause dangerous spikes in blood pressure (rebound hypertension) especially when taken with a beta-blocker.
7. Diuretics – (3 classes – Thiazide Diuretics, Loop Diuretics, Potassium Sparing Diuretics) - Diuretics work by causing the kidneys to excrete sodium and water in the urine, resulting in less in the blood and hence lower blood pressure.