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Terazosin exerts a selective postsynaptic action, inhibiting the binding of norepinephrine to the α1 receptors.

Three α1 receptor subtypes have been identified, α1a, α1b and α1d:

  • α1a and α1d subtypes are predominant in the prostate, bladder, and detrusor muscle.
  • α1b subtypes are largely located on vascular smooth muscle.

Terazosin antagonizes all three subtypes; blockade of α1a and α1d can lead to smooth muscle relaxation in the lower urinary tract resulting in improved urinary flow rates. At the same time blockade of α1b subtypes can cause relaxation in peripheral vascular resistance which results in a decrease in blood pressure.


  • Treatment of symptomatic benign prostatic hyperplasia (BPH)
  • Treatment of hypertension, alone or in combination with other antihypertensive agents such as diuretics or beta-blockers.

[edit] DOSAGE

  • Benign Prostatic Hyperplasia: Initial Dose is 1 mg at bedtime. The dose should be slowly increased to 2 mg, 5 mg, or 10 mg once daily to achieve the desired improvement of symptoms
  • Hypertension: Initial Dose is 1 mg at bedtime, to be slowly increased to the usual recommended dose range (1 mg to 5 mg) administered once a day.


  • Hypersensitivity to Terazosin


  • Postural hypotension, dizziness, lightheadedness and syncope can occur, especially at initiation of therapy. treatment should always be initiated with a 1 mg given at bedtime, dosage should then be increased slowly.
  • Rarely, (probably less than once in every several thousand patients), terazosin and other α1 antagonists have been associated with priapism
  • Patients should be screened for the presence of prostate cancer prior to treatment and at regular intervals afterwards because prostate cancer causes many of the symptoms associated with BPH and the two disorders frequently co-exist.
  • Drowsiness or somnolence can occur with Terazosin tablets, requiring caution in people who must drive or operate heavy machinery


  • Concomitant administration of Terazosin with a PDE5 inhibitor (Viagra, Levitra, Cialis, Stendra) can result in additive blood pressure lowering effects and symptomatic hypotension.


  • Pregnancy Category C (US). Terazosin is not recommended during pregnancy unless the potential benefit justifies the potential risk to the mother and fetus.
  • Nursing Mothers: It is not known whether terazosin is excreted in breast milk. Because many drugs are excreted in breast milk, caution should be exercised when Terazosin is administered to a nursing woman.


  • Possible adverse events include: First-dose syncope due to excessive orthostatic hypotension (Take first dose just before bedtime to lessen likelihood of first dose effect), Asthenia, postural hypotension, dizziness, somnolence, nasal congestion/rhinitis, and impotence.


Benign Prostatic Hyperplasia (BPH) and Treatments (Video 1)
Benign Prostatic Hyperplasia (BPH) and Treatments (Video 2)



ACE inhibitors Benazepril (Lotensin)   Captopril (Capoten)   Cilazapril   Delapril   Enalapril (Renitec, Vasotec)   Fosinopril (Monopril)  Lisinopril (Prinivil, Zestril)   Moexipril (Univasc)  Perindopril (Aceon)  Quinapril (Accupril)  Ramipril (Altace, Triatec)   Trandolapril (Mavik)  Zofenopril (Bifril, Zopranol)
Angiotensin II receptor antagonist Azilsartan (Edarbi)   Candesartan (Atacand)   Eprosartan (Teveten)   Irbesartan (Aprovel, Avapro, Karvea)   Losartan (Cozaar)   Olmesartan (Benicar, Olmetec)   Telmisartan (Micadis)   Valsartan (Diovan, Tareg)
Renin inhibitors Aliskiren (Rasilez, Tekturna)
Alpha-1 blockers Doxazosin (Cardura)   Prazosin (Minipress)   Terazosin (Hytrin)
Alpha-2 agonists (centrally acting) Clonidine (Oral route)   Clonidine (Transdermal) (Catapresan)   Guanfacine (Tenex)   Methyldopa (Aldomet)
Calcium channel blockers Dihydropyridines‎ Amlodipine (Norvasc)   Barnidipine (Vasexten)   Felodipine (Plendil)   Isradipine (Dynacirc)   Lacidipine (Lacipil, Motens)   Lercanidipine (Zanidip)   Manidipine   Nicardipine   Nifedipine (Adalat)   Nisoldipine   Nitrendipine
Benzothiazepine‎ Diltiazem (Cardizem, Taztia XT, Tiazac, Tildiem)
Phenylalkylamine‎ Gallopamil   Verapamil (Calan)
Beta blockers Beta1 selective (cardioselective) Acebutolol (Sectral)   Atenolol (Tenormin)   Betaxolol (Kerlon)   Bisoprolol (Concor)   Celiprolol (Cordiax)   Metoprolol (Betaloc, Lopressor, Toprol-XL)   Nebivolol (Bystolic, Lobivon, Nebilox)
Nonselective (Beta1 and Beta2 blockers) Oxprenolol (Trasitensin)   Propranolol (Inderal)   Timolol (Blocadren)
Nonselective (Beta1, Beta2 and Alpha1 blockers) Carvedilol (Dilatrend)   Labetalol (Trandate)
Beta blocker with intrinsic sympathomimetic activity (ISA) Acebutolol (Sectral)   Celiprolol (Cordiax)
Lipophilic Beta blockers Propranolol (Inderal)   Metoprolol (Betaloc, Lopressor, Toprol-XL)   Oxprenolol (Trasitensin)
Diuretics Carbonic anhydrase inhibitors Acetazolamide (Diamox)
Loop diuretics Bumetanide   Etacrynic acid   Furosemide (Lasix)   Piretanide   Torasemide (Demadex)
Thiazide diuretics Chlorothiazide (Diuril)   Hydrochlorothiazide (Esidrex)
Thiazide-like diuretics Chlortalidone (Hygroton)   Indapamide (Lozol, Lozide)   Metolazone
Potassium-sparing diuretics Epithelial sodium channel blockers: Amiloride (Midamor)   Triamterene (Dyrenium)
Aldosterone receptor antagonists: Potassium canrenoate   Eplerenone (Inspra)   Spironolactone (Aldactone)
Osmotic diuretics Mannitol
Combination therapy Amiloride/Hydrochlorothiazide (Moduretic)   Spironolactone/Hydrochlorothiazide (Aldactazide)
Benign Prostatic Hypertrophy
5α reductase inhibitors Dutasteride (Avodart)   Finasteride (Proscar)
Alpha 1 antagonists Alfuzosin (Uroxatral, Xatral)   Doxazosin (Cardura)   Prazosin   Silodosin (Silodyx, Rapaflo)   Tamsulosin (Omnic, Flomax, Secotex)   Terazosin (Hytrin)
Phytotherapy Pygeum africanum   Serenoa repens
PDE5 inhibitors Tadalafil (Cialis)
Combination products Dutasteride/Tamsulosin (Combodart, Jalyn, Duodart)
Other Mepartricin
Veterinary Osaterone (Ypozane)