Complications: Diuretics are among the top five classes of drugs causing adverse effects leading to hospitalization.
Diuretics have the lowest adherence rate because of their side effects, which include frequent urination, tiredness, dizziness, cramps, and weakness.
Low potassium levels can lead to irregular heart rhythms and related sudden death, muscle weakness, and balance problems.
Low sodium may contribute to confusion, delirium, and irreversible brain damage, adding to age-related dementia.
Some diuretics, such as HCTZ, are strongly linked to an increased risk of developing diabetes.
Long-term use of diuretics is associated with an increased risk of kidney cancer (renal cell carcinoma).
For most cases of high blood pressure there is no known cause. This is called primary hypertension. For others, certain medical conditions like kidney or heart conditions can cause high blood pressure. This is called secondary hypertension. Some medications like birth control pills or over-the-counter cold medicines can cause high blood pressure as well. Blood pressure may or may not return to normal upon discontinuation of the medication. 
Diuretics, sometimes called water pills, are medications that act on your kidneys to help your body eliminate sodium and water, reducing blood volume.
Causes of High Blood Pressure:
1. Thiazide diuretics.
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Commonly used medications for hypertension treatments
Alpha blockers. These medications reduce nerve impulses to blood vessels, reducing the effects of natural chemicals that narrow blood vessels. Alpha blockers include doxazosin (Cardura), prazosin (Minipress) and others.
Beta blockers. These medications reduce the workload on your heart and open your blood vessels, causing your heart to beat slower and with less force. Beta blockers include acebutolol (Sectral), atenolol (Tenormin) and others.
When prescribed alone, beta blockers don't work as well, especially in older adults, but may be effective when combined with other blood pressure medications.
Calcium channel blockers. These medications - including amlodipine (Norvasc), diltiazem (Cardizem, Tiazac, others) and others - help relax the muscles of your blood vessels. Some slow your heart rate. Calcium channel blockers may work better for older people and blacks than do ACE inhibitors alone.
Angiotensin II receptor blockers (ARBs). These medications help relax blood vessels by blocking the action, not the formation, of a natural chemical that narrows blood vessels. ARBs include candesartan (Atacand), losartan (Cozaar) and others. People with chronic kidney disease may benefit from having an ARB as one of their medications.
Alpha blockers complications: Weakness or fatigue.
Lightheadedness, dizziness, or fainting when you stand up suddenly after sitting or lying down, postural or orthostatic hypotension, Headaches, Nasal congestion 
Beta blockers complications: Fatigue, Cold hands, Headache, Upset stomach, Constipation, Diarrhea, Dizziness Shortness of breath, Trouble sleeping, Loss of sex drive/erectile dysfunction, depression
Calcium channel blockers complications: Headache, constipation, rash, nausea, flushing, edema (fluid accumulation in tissues), drowsiness, low blood pressure, and dizziness. Sexual dysfunction, overgrowth of gums, and liver dysfunction also have been associated with calcium channel blockers. Verapamil (Covera-HS, Verelan PM, Calan) and diltiazem (Cardizem LA, Tiazac) worsen heart failure because they reduce the ability of the heart to contract and pump blood.
Angiotensin receptor blockers complications: Headache, Dizziness, Lightheadedness, Nasal congestion, Back and leg pain, Diarrhea, Kidney failure, Liver failure, Allergic reaction, A drop in white blood cells, Localized swelling of tissues (angioedema)
Angiotensin-converting enzyme (ACE) inhibitors. These medications - such as lisinopril (Zestril), benazepril (Lotensin), captopril (Capoten) and others - help relax blood vessels by blocking the formation of a natural chemical that narrows blood vessels. People with chronic kidney disease may benefit from having an ACE inhibitor as one of their medications
Renin inhibitors. Aliskiren (Tekturna) slows down the production of renin, an enzyme produced by your kidneys that starts a chain of chemical steps that increases blood pressure.
Tekturna works by reducing the ability of renin to begin this process. Due to a risk of serious complications, including stroke, you shouldn't take aliskiren with ACE inhibitors or ARBs.
ACE inhibitors complications: Dizziness, headache, drowsiness, diarrhea, low blood pressure, weakness, cough, and rash.
ACE inhibitors may cause birth defects and, therefore, should not be used during pregnancy.
Other side effects of ACE inhibitors include kidney failure, allergic reactions, a decrease in white blood cells, and swelling of tissues (angioedema).
Renin inhibitors complications: Angioedema (BE: angiooedema) or Quincke's edema
4. Other medications
Central-acting agents. These medications prevent your brain from signaling your nervous system to increase your heart rate and narrow your blood vessels. Examples include clonidine (Catapres, Kapvay), guanfacine (Intuniv, Tenex) and methyldopa.
Aldosterone antagonists. Examples are spironolactone (Aldactone) and eplerenone (Inspra). These drugs block the effect of a natural chemical that can lead to salt and fluid retention, which can contribute to high blood pressure
Vasodilators. These medications, including hydralazine and minoxidil, work directly on the muscles in the walls of your arteries, preventing the muscles from tightening and your arteries from narrowing
Central-acting agents complications: Depression, dizziness, drowsiness, slow heartbeat, dry mouth, nausea, skin rash, sleep disturbances, liver problems, anemia or low blood count
Aldosterone antagonists complications: Trouble breathing.Swelling of your face, lips, tongue, or throat. Confusion. Irregular heartbeat. Numbness or tingling in your hands, feet, or lips. Nausea and vomiting.Stomach cramps.Diarrhea.
Vasodilators complications: Headaches, a flushed appearance or skin rashes, rapid or irregular heart beat, weight gain, swelling of feet or lower legs, upset stomach, chest pain, shortness of breath or numbness.