Understanding Your Blood Pressure Medication

Many blood pressure medications, known as antihypertensives, are available by prescription to lower high blood pressure (HBP or hypertension). There are a variety of classes of high blood pressure medications and they include a number of different drugs. In the tables below, you will find an overview of the classes of blood pressure medication, and what they do.

What are the types of Blood Pressure Medications?

In the tabs below, you’ll find summaries of some of the major types of commonly prescribed cardiovascular medications. If your prescription medication isn’t on this list, remember that your healthcare provider and pharmacist are your best sources of information. There are a lot of medication brands and names out there, this list is NOT meant as a recommendation. It's important to discuss all of the drugs you take with your doctor and understand what they are supposed to help. NEVER stop taking a medication and NEVER change your dose or frequency without first consulting your doctor. And ALWAYS keep monitoring blood pressure regularly, check your blood pressure baseline, and eat healthfully to make troubleshooting medications easier for your provider.

The classes of blood pressure medications include:

• Diuretics
• Beta-blockers
• ACE inhibitors
• Angiotensin II receptor blockers
• Calcium channel blockers
• Alpha blockers
• Alpha-2 Receptor Agonists
• Combined alpha and beta-blockers
• Central agonists
• Peripheral adrenergic inhibitors
• Vasodilators

Diuretics

Diuretics help the body get rid of excess sodium (salt) and water and help control blood pressure. They are often used in combination with additional prescription therapies.

Some noted possible side effects from diuretics:

Some of these drugs may decrease your body's supply of the mineral potassium. Symptoms such as weakness, leg cramps or being tired may result. Eating foods containing potassium may help prevent significant potassium loss. If your doctor recommends it, you could prevent potassium loss by taking a liquid or tablet that has potassium along with the diuretic. Diuretics such as amiloride (Midamar)*, spironolactone (Aldactone)* or triamterene (Dyrenium)* are called "potassium sparing" agents. They don't cause the body to lose potassium. They might be prescribed alone, but are usually used with another diuretic.

Beta-blockers

Beta-blockers reduce the heart rate, the heart's workload and the heart's output of blood, which lowers blood pressure.

• If you have diabetes and you're taking insulin, have your responses to therapy monitored closely.

• If you have been prescribed beta-blockers, consult your healthcare provider prior to conception if you are considering pregnancy or if there is a chance you could become pregnant. If you discover that you are pregnant consult your healthcare provider as soon as possible to determine the safest medication for you at this time.

ACE inhibitors

Angiotensin is a chemical that causes the arteries to become narrow, especially in the kidneys but also throughout the body. ACE stands for Angiotensin-converting enzyme. ACE inhibitors help the body produce less angiotensin, which helps the blood vessels relax and open up, which, in turn, lowers blood pressure.

Angiotensin II receptor blockers

These drugs block the effects of angiotensin, a chemical that causes the arteries to become narrow. Angiotensin needs a receptor- like a chemical "slot" to fit into or bind with- in order to constrict the blood vessel. ARBs block the receptors so the angiotensin fails to constrict the blood vessel. This means blood vessels stay open and blood pressure is reduced.

Calcium channel blockers

This drug prevents calcium from entering the smooth muscle cells of the heart and arteries. When calcium enters these cells, it causes a stronger and harder contraction, so by decreasing the calcium, the hearts' contraction is not as forceful. Calcium channel blockers relax and open up narrowed blood vessels, reduce heart rate and lower blood pressure.

Alpha blockers

These drugs reduce the arteries' resistance, relaxing the muscle tone of the vascular walls.

Alpha-2 Receptor Agonists

These drugs reduce blood pressure by decreasing the activity of the sympathetic (adrenaline-producing) portion of the involuntary nervous system. Methyldopa is considered a first line antihypertensive during pregnancy because adverse effects are infrequent for the pregnant woman or the developing fetus.

Combined alpha and beta-blockers

Combined alpha and beta-blockers are used as an IV drip for those patients experiencing a hypertensive crisis. They may be prescribed for outpatient high blood pressure use if the patient is at risk for heart failure.

Central agonists

Central agonists also help decrease the blood vessels' ability to tense up or contract. The central agonists follow a different nerve pathway than the alpha and beta-blockers, but accomplish the same goal of blood pressure reduction.

Generic nameCommon brand namesalpha methyldopaAldomet*clonidine hydrochlorideCatapres*guanabenz acetateWytensin*guanfacine hydrochlorideTenex*

Peripheral adrenergic inhibitors

These medications reduce blood pressure by blocking neurotransmitters in the brain. This blocks the smooth muscles from getting the "message" to constrict. These drugs are rarely used unless other medications don't help.

Some noted possible side effects of peripheral adrenergic inhibitors:

• Guanadrel (Hylorel)* or guanethidine (Ismelin)* may cause some diarrhea, which may persist in some people. This side effect usually becomes less of a problem if you continue treatment. These drugs reduce blood pressure more when you stand. Consequently, you may get dizzy and lightheaded and feel weak when you get out of bed in the morning or stand up suddenly. If you notice any of these reactions and if they persist for more than a minute or two, contact your doctor. He/she may instruct you to reduce or omit the next dose of the medication.
• When taking guanethidine, don't stand in the hot sun or at a social gathering if you begin to feel faint or weak. These activities cause low blood pressure and fainting. Male patients may experience impotence. Contact your doctor if either of these side effects occurs.

Blood vessel dilators (vasodilators)

Blood vessel dilators, or vasodilators, can cause the muscle in the walls of the blood vessels (especially the arterioles) to relax, allowing the vessel to dilate (widen). This allows blood to flow through better.

Some noted possible side effects of vasodilators:

• Hydralazine (Apresoline)* may cause headaches, swelling around the eyes, heart palpitations or aches and pains in the joints. Usually none of these symptoms are severe, and most will go away after a few weeks of treatment. This drug isn't usually used by itself.
• Minoxidil (Loniten)* is a potent drug that's usually used only in resistant cases of severe high blood pressure. It may cause fluid retention (marked weight gain) or excessive hair growth.

Adapted from the American Heart Association. For more information on side effects of different drug classes, go here.