Drugs for high blood pressure, or hypertension, have been associated with more than a 30 percent reduction in the risk of heart disease and stroke, according to the National Heart, Lung, and Blood Institute. Like all medications, however, high blood pressure drugs can cause side effects. Low blood pressure, or hypotension, is a potential side effect of any antihypertensive drug. Side effects unique to specific blood pressure medications are also possible.
Diuretic medications, or water pills, stimulate the kidneys to release salt and water from the body, which lowers blood pressure. Hydrochlorothiazide (Microzide), chlorothiazide (Diuril), chlorthalidone (Thalitone) and furosemide (Lasix) are diuretics that may be prescribed for blood pressure control. Since they affect the body's water balance, diuretics lead to shifts in sodium and potassium levels. Both hypokalemia, or low potassium levels, and hyponatremia, or low sodium levels, are possible. Hypokalemia occurs more frequently and may cause muscle cramps and weakness. Blood work is typically done on a regular basis to monitor electrolyte levels and kidney function. Diuretics can also sometimes lead to gout flareups in people with a history of the condition. The dose of diuretic can be adjusted to minimize the risk of future gout attacks.
Beta Blockers and Calcium Channel Blockers
Beta blockers and calcium channel blockers act directly on the heart and blood vessels to control blood pressure. Atenolol (Tenormin), labetalol (Trandate) and bisoprolol (Zebeta) are beta blockers often used to treat high blood pressure. Fatigue and depressed mood are potential beta blocker side effects. Impotence is possible as well. These side effects can sometimes be offset by changing the dose or time of day the medication is taken. Beta blockers can also lead to a slow heart rate, as can the calcium channel blockers verapamil (Isoptin, Covera-HS) and diltiazem (Cardizem, Cartia XT). As a result, beta blockers generally shouldn't be taken with verapamil or diltiazem, as this can cause dizziness and fainting.
Angiotensin-Converting Enzyme Inhibitors
Angiotensin-converting enzyme inhibitors, or ACEIs, and angiotensin receptor blockers, known as ARBs, prevent a hormone called renin from increasing blood pressure. ACEIs and ARBs commonly used for high blood pressure include lisinopril (Zestril, Prinivil), enalapril (Vasotec), valsartan (Diovan) and olmesartan (Benicar). ACEIs can lead to a persistent, dry cough. The cough clears up once the drug has been stopped and does not occur with the use of ARBs. If you may be pregnant and are taking an ACEI or ARB, consult your doctor immediately, as these drugs are toxic to the developing fetus. Angioedema, or severe swelling, is a rare side effect of ACEIs and, to a lesser extent, a side effect of ARBs. The release of proteins that promote fluid accumulation and swelling are thought to contribute to angioedema. Angioedema can affect any body part, but when it involves the lips, tongue or airway, it can be a life-threatening emergency. If angioedema is suspected, the offending medication should be discontinued immediately.
Medications that affect the alpha receptors in the brain and blood vessels and help to regulate blood pressure include clonidine (Catapres), doxazosin (Cardura, Cardura XL), prazosin (Minipress) and terazosin (Hytrin). Clonidine can cause fatigue as well as dry mouth. Additionally, clonidine should not be stopped abruptly, because this can cause dangerous spikes in blood pressure --what's known as rebound hypertension. Doxazosin, prazosin and terazosin can lead to headache, palpitations and dizziness. These medications must generally be started at low doses to minimize dizziness and reduce the risk of fainting.