Diuretics

Diuretics, sometimes called water pills, help rid your body of sodium and water. They work by making your kidneys excrete more sodium in urine. The sodium, in turn, takes water with it from your blood. That decreases the amount of fluid flowing through your blood vessels, which reduces pressure on the walls of your arteries.

Examples of diuretics
There are three types of diuretics: thiazide, loop and potassium-sparing. Each works by affecting a different part of your kidneys, and each may have different uses, side effects and precautions. Which diuretic is best for you depends on your health and the condition being treated.

Examples of thiazide diuretics include:

• Hydrochlorothiazide
•   Metolazone

Examples of potassium-sparing diuretics include:

• Spironolactone
• Eplerenone

Different types of diuretics may also be combined into one pill.

Side effects and cautions
In general, potential side effects of diuretics include increased urination, weakness, dizziness, impotence, dehydration and, depending on the type of diuretic, potassium decrease or increase, or sodium decrease.

Beta blockers
Beta blockers reduce blood pressure. Beta blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. As a result, the heart beats more slowly and with less force, thereby reducing blood pressure. Beta blockers also help blood vessels relax and open up to improve blood flow.

Examples of beta blockers
Some beta blockers mainly affect your heart, while others affect both your heart and your blood vessels. Which one is best for you depends on your health and the condition being treated. Beta blockers are also known as beta-adrenergic blocking agents.

Examples of beta blockers include:

• Atenolol
• Metoprolol
• Propranolol

Side effects and cautions

Common side effects of beta blockers include fatigue, cold hands, dizziness and weakness. Less common side effects include shortness of breath, trouble sleeping, loss of sex drive and slow heartbeat.

Beta blockers generally aren't used in people with asthma because of concerns that the medication may trigger severe asthma attacks.

Beta blockers can also affect your lipid levels, causing a slight increase in triglycerides and a modest decrease in high-density lipoprotein, the "good" cholesterol. These changes often are temporary. You should not abruptly stop taking a beta blocker because doing so could increase your risk of a heart attack or other heart problems.

Calcium channel blockers
Calcium channel blockers prevent calcium from entering cells of the heart and blood vessel walls. This results in lower blood pressure. Calcium channel blockers, also called calcium antagonists, relax and widen blood vessels by affecting the muscle cells in the arterial walls.

Some of the medications in this class have the added benefit of slowing your heart rate, which can further lower blood pressure.

Examples of calcium channel blockers
There are two types of calcium channel blockers: short-acting and long-acting. Short-acting medications work quickly, but their effects last only a few hours. Long-acting medications take longer to start working, but their effects last longer.

Several calcium antagonists are available. Which one is best for you depends on your health and the condition being treated.

Examples of calcium antagonists include:

• Amlodipine
• Diltiazem
• Nifedipine
• Verapamil 

Under special circumstances, your doctor might prescribe a calcium channel blocker along with other high blood pressure drugs or with cholesterol-lowering drugs such as statins.

Side effects and cautions
Side effects of calcium channel blockers include constipation, headache, rapid heartbeat, rash, drowsiness, flushing, nausea, and swelling in the feet and lower legs.

Certain calcium channel blockers interact with grapefruit products. Don't take these medications with grapefruit or grapefruit juice because they can reduce your liver's ability to eliminate calcium channel blockers from your body, allowing the medications to build up in your body.

Angiotensin-converting enzyme (ACE) inhibitors
Angiotensin-converting enzyme (ACE) inhibitors help relax blood vessels. ACE inhibitors prevent an enzyme in your body from producing angiotensin II, a substance in your body that affects your cardiovascular system in numerous ways, including narrowing your blood vessels. This narrowing can cause high blood pressure and force your heart to work harder.

Numerous ACE inhibitors are available. Which one is best for you depends on your health and the condition being treated.

Examples of ACE inhibitors include:
Benazepril
Enalapril
Lisinopril

Side effects and cautions
Side effects include dry cough, increased blood-potassium level, rash, dizziness, lightheadedness, changes in taste and reduced appetite over long intervals. In rare cases — but more commonly in blacks and in smokers — ACE inhibitors can cause localized areas of your tissues to swell (angioedema). If it occurs in the throat, that swelling can be life-threatening.

Because ACE inhibitors can cause birth defects, don't take them if you are pregnant or plan to become pregnant.

Angiotensin II receptor blockers (ARBs)
Angiotensin II receptor blockers help relax your blood vessels. Doing so lowers your blood pressure and makes it easier for your heart to pump blood.

Angiotensin II is a natural substance in your body that affects your cardiovascular system in many ways, such as by narrowing your blood vessels. This narrowing can increase your blood pressure and force your heart to work harder. Angiotensin II also stimulates the release of aldosterone, a hormone that increases your body's retention of sodium and water, which can lead to increased blood pressure. It can also thicken and stiffen the walls of your blood vessels and heart.

Angiotensin II receptor blockers block the action of angiotensin II. That allows blood vessels to widen (dilate). Angiotensin II receptor blockers are similar to angiotensin-converting enzyme (ACE) inhibitors. But while angiotensin II receptor blockers block the action of angiotensin II, ACE inhibitors block the actual production of angiotensin II.

Numerous angiotensin II receptor blockers are available. Which one is best for you depends on your health and the condition being treated.

Examples of angiotensin II receptor blockers include:

Side effects and cautions
Side effects of angiotensin II receptor blockers may include headache, dizziness, lightheadedness, nasal congestion, back and leg pain, and diarrhea. Rare but more serious side effects include kidney failure, liver failure, allergic reaction, a drop in white blood cells and localized swelling of tissues (angioedema).

Because angiotensin II receptor blockers can cause birth defects, don't take them if you're pregnant or plan to become pregnant.

Alpha blockers
Alpha blockers relax certain muscles and help small blood vessels remain open. They work by keeping the hormone norepinephrine (noradrenaline) from stimulating the muscles in the walls of smaller arteries and veins. This stimulation makes the vessel walls constrict. Blocking that effect causes the vessels to remain open and relaxed. This improves blood flow and lowers blood pressure.

Because alpha blockers also relax smooth muscle cells throughout the body, these medications help improve urine flow in older men with prostate problems.

Many alpha blockers are available, in either short-acting or long-acting forms. Short-acting medications work quickly, but their effects last only a few hours. Long-acting medications take longer to start working, but their effects last longer. Which one is best for you depends on your health and the condition being treated.

Alpha blockers are also called alpha-adrenergic blocking agents, alpha-adrenergic antagonists, adrenergic blocking agents and alpha-blocking agents.

Examples of alpha blockers include:

• Doxazosin
• Prazosin
• Terazosin
• Tamsulosin
• Alfuzosin

Side effects and cautions
Alpha blockers may have what's called a "first-dose effect." When you first start taking an alpha blocker, you may develop pronounced low blood pressure and dizziness, which can make you suddenly faint when you rise from a sitting or lying position.

Other side effects include headache, pounding heartbeat, nausea, weakness, weight gain and small decreases in low-density lipoprotein cholesterol (the "bad" cholesterol).

Of concern are the results of a major high blood pressure study referred to as the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). It indicated that some alpha blockers can increase the risk of heart failure with long-term use. Talk to your doctor about your situation.

Central-acting agents
Central-acting agents lower your heart rate and reduce your blood pressure. They work by preventing your brain from sending signals to your nervous system to speed up your heart rate and narrow your blood vessels. As a result, your heart doesn't pump as hard and your blood flows more easily through your blood vessels.

Central-acting agents are also called central adrenergic inhibitors, central alpha agonists and central agonists. Several central-acting agents are available. Which one is best for you depends on your health and the condition being treated.

Examples of central-acting agents include:

• Clonidine
• Guanfacine
• Methyldopa

Side effects and cautions
These medications can have strong side effects, so they aren't commonly used. Side effects include extreme fatigue, drowsiness or sedation, dizziness, impotence, constipation, dry mouth, headache, weight gain, impaired thinking and psychological problems, such as depression.

Abruptly stopping use of some central-acting agents can cause a sudden, dangerous increase in blood pressure. Don't stop taking these medications without talking to your doctor.

Vasodilators
Vasodilators are medications that open (dilate) blood vessels. They work directly on the muscles in the walls of your arteries, preventing the muscles from tightening and the walls from narrowing. As a result, blood flows more easily through your arteries, your heart doesn't have to pump as hard and blood pressure is reduced.

Several vasodilators are available. Which one is best for you depends on your health and the condition being treated.

Examples of vasodilators include:

• Hydralazine
• Minoxidil

Side effects and cautions
Vasodilators are potent medications and are generally used only as a last resort, when other medications haven't adequately controlled your blood pressure.

These medications have a number of side effects, some of which require taking other medications to counter those effects.

Side effects include chest pain, rapid heartbeat, heart palpitations, fluid retention (edema), nausea, vomiting, dizziness, flushing, headache, nasal congestion and excessive hair growth. In addition, some vasodilators can increase your risk of developing lupus, a connective tissue disease.