Skip to Content

Terazosin Hydrochloride

Class: alpha-Adrenergic Blocking Agents
VA Class: CV150
Chemical Name: Piperazine, 1-(4-amino-6,7-dimethoxy-2-quinazolinyl)-4-((tetrahydro-2-furanyl-)carbonyl)-, monohydrochloride, dihydrate
CAS Number: 70024-40-7

Medically reviewed by Last updated on Feb 13, 2019.


Postsynaptic α1-adrenergic blocking agent; quinazoline derivative.1 2 3 4 5 6 8 9 10

Uses for Terazosin Hydrochloride


Management of hypertension (alone or in combination with other classes of antihypertensive agents).1 3 4 6 8 11 12 13 14 30 31 32 500

Not considered a preferred agent for initial management of hypertension, but may be useful in the management of resistant hypertension as a component of combination therapy.501 502 503 504

Most effective when used in combination with a diuretic; beneficial effects of α1-blockers on blood glucose and lipid concentrations also may mitigate some adverse metabolic effects of diuretics.504

Some experts state that an α1-blocker may be a useful component of antihypertensive treatment regimens in older men with coexisting benign prostatic hyperplasia (BPH);504 however, the American Urology Association (AUA) states that monotherapy with these drugs is not optimal in hypertensive patients with lower urinary tract symptoms (LUTS) or BPH and that such conditions should be managed separately.230

Benign Prostatic Hyperplasia

Reduction of urinary obstruction and relief of associated manifestations in patients with symptomatic BPH.1 5 9 17 18 21 23 25 33

Although drug therapy usually is not as effective as surgical therapy, it may provide adequate symptomatic relief with fewer and less serious adverse effects compared with surgery.59

May consider combined therapy with an α1-adrenergic blocker and 5α-reductase inhibitor for men with bothersome moderate to severe BPH and demonstrable prostatic enlargement.59 Has been more effective than therapy with either drug alone in preventing long-term BPH symptom progression.59 Men at risk for BPH progression are most likely to benefit from combination therapy.59

Terazosin Hydrochloride Dosage and Administration



  • Carefully monitor BP during initial titration or subsequent upward dosage adjustment.500 501

  • Goal is to achieve and maintain optimal control of BP; individualize specific target BP based on consideration of multiple factors, including patient age and comorbidities, and currently available evidence from clinical studies.500 501


Oral Administration

Food may delay time to peak plasma concentrations by about 40 minutes but has little effect on extent of absorption.1 28 Manufacturer makes no specific recommendations regarding administration with meals.1


Administer initial dose at bedtime; may administer maintenance doses in the morning.1

Administer once daily or, if needed for optimal BP control, in 2 divided doses at 12-hour intervals.1 500


Administer once daily at bedtime.1


Available as terazosin hydrochloride; dosage expressed in terms of terazosin.1

Individualize dosage according to patient response and tolerance.1 3 Initiate at low dosage to minimize frequency of postural hypotension and syncope.1

Monitor BP 2–3 hours after dosing and at end of dosing interval to determine whether peak and trough responses are similar and to assess potential manifestations (e.g., dizziness, palpitations) of an excessive response.1

If therapy is interrupted for several days or longer, restart using initial dosage regimen.1

Pediatric Patients


Initially, 1 mg once daily.76 Increase dosage as necessary up to a maximum of 20 mg once daily.76



Initially, 1 mg daily at bedtime.1 3 May increase dosage gradually to 5 mg daily,1 3 with further titration up to 20 mg daily if BP is not controlled.1 500

Each increase should be delayed until BP has stabilized at a given dosage.1 3


Initially, 1 mg daily at bedtime.1 9 May increase daily dosage to 2 mg and thereafter to 5 mg and 10 mg, if necessary, to reduce symptoms and/or improve urinary flow rates.1 9

Prescribing Limits

Pediatric Patients


Maximum 20 mg daily.76



Maximum 40 mg daily;1 however, dosages >20 mg daily do not appear to improve BP control.1 3


Maximum 20 mg daily.1

Special Populations

Hepatic Impairment

Manufacturer makes no specific dosage recommendations; effects on the pharmacokinetics of terazosin have not been elucidated.1

Renal Impairment

Clinically important alterations in the pharmacokinetics of terazosin not observed to date;1 3 28 29 dosage adjustment not necessary.3 28 29 33

Administration of supplemental doses of the drug following hemodialysis does not appear to be necessary.1

Geriatric Patients

Use with caution; generally, increase dosage more slowly in geriatric patients than in younger adults.7 9

Cautions for Terazosin Hydrochloride


  • Known hypersensitivity to terazosin, quinazolines (e.g., doxazosin, prazosin), or any ingredient in the formulation.1 33



Postural Hypotension

Marked hypotension, especially in the upright position, can occur; may be accompanied by syncope, palpitations, and other postural effects (e.g., dizziness, lightheadedness, vertigo).1 2 3 4 6 9 13 30

Postural effects are most common after an initial dose, shortly after dosing (e.g., within 90 minutes), when dosage is increased, or when therapy is resumed after an interruption exceeding a few days.1

To decrease risk of excessive hypotension and syncope, initiate therapy at low dose and titrate carefully, lessen level of salt restriction, and avoid diuretics just prior to initiation of terazosin therapy.1 3 4 6 30


Priapism reported rarely; may lead to permanent impotence if not treated promptly.1 48 49 (See Advice to Patients.)

General Precautions

Prostate Cancer

Exclude possibility of prostate cancer before initiation of therapy for BPH.1 9

Specific Populations


Category C.1


Not known whether terazosin is distributed into milk.1 Caution if used in nursing women.1

Pediatric Use

Safety and efficacy not established in patients <21 years of age.1 33

Geriatric Use

Geriatric patients may be particularly susceptible to postural effects and other adverse effects.9 (See Geriatric Patients under Dosage and Administration.)

Common Adverse Effects

In the treatment of hypertension: dizziness, headache, asthenia (weakness, tiredness, lassitude, fatigue), nasal congestion, peripheral edema, somnolence, nausea, palpitation.1 3 4 6 13

In the treatment of BPH: dizziness, asthenia, headache, postural hypotension, somnolence.1 9

Interactions for Terazosin Hydrochloride

Antihypertensive Agents

Possible rapid fall in BP and exacerbation of postural effects.1 9 Use with caution; may need to reduce and/or retitrate dosage.1

Specific Drugs




No interaction observed1

β-Adrenergic blocking agents (e.g., atenolol, propranolol)

No interaction observed1


No interaction observed1


No interaction observed1

Antihistamines (e.g., chlorpheniramine)

No interaction observed1


Increased peak plasma concentrations of terazosin1


No interaction observed1


No interaction observed1


No interaction observed1


No interaction observed1

Diuretics, thiazide (e.g., hydrochlorothiazide)

No interaction observed1


No interaction observed1

Hypoglycemic agents

No interaction observed1

NSAIAs (e.g., aspirin, ibuprofen, indomethacin)

No interaction observed1

Sympathomimetic (adrenergic) agents (e.g., phenylephrine, pseudoephedrine)

No interaction observed1


Increased AUC of terazosin; decreased time to peak plasma terazosin concentrations1

Terazosin Hydrochloride Pharmacokinetics



Rapidly and almost completely absorbed from the GI tract following oral administration.1 2 Peak plasma concentration attained in about 1 hour.1


Food has minimal effect on extent of absorption; however, time to peak plasma concentration is delayed by about 40 minutes.1 28



Not known whether terazosin is distributed into breast milk.1

Plasma Protein Binding

90–94%.1 a



Extensively metabolized in the liver,a with minimal first-pass metabolism.1

Elimination Route

Excreted in urine (40%) and in feces (60%).1


Adults: approximately 12 hours.1

Geriatric patients: approximately 14 hours.1

Special Populations

In geriatric patients, plasma clearance is decreased by about 30%.1





20–25°C.1 Protect from light and moisture.1


  • Reduces peripheral vascular resistance and BP as a result of vasodilating effects; produces both arterial and venous dilation.1 3 4 6 10

  • Binds to α1-adrenergic receptors in the prostate and the bladder trigone, resulting in decreased urinary outflow resistance in men.5 9

  • May improve to limited extent the serum lipid profile (e.g., small increases in HDL/total cholesterol ratio; small decreases in LDL, total cholesterol, and triglyceride concentrations).1 3 8 9 10 11 28 31 32

Advice to Patients

  • Possible syncopal and orthostatic symptoms, especially at initiation of therapy; importance of avoiding driving or other hazardous tasks for 12 hours after first dose, a dosage increase, or when resumed after therapy interruption.1 9

  • Importance of sitting or lying down when symptoms of lowered BP occur, and of rising carefully from a sitting or lying position.1

  • Importance of informing clinician if bothersome dizziness, lightheadedness, or palpitations occur.1

  • Possible drowsiness or somnolence; use caution when operating machinery or driving a motor vehicle until effects on individual are known.1 9

  • Importance of men seeking medical treatment if painful or sustained (for hours) erection occurs.1 48 49

  • Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.1

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as concomitant illnesses.1

  • Importance of advising patients of other important precautionary information.1 (See Cautions.)


Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

Terazosin Hydrochloride


Dosage Forms


Brand Names




1 mg (of terazosin)*

Terazosin Hydrochloride Capsules

2 mg (of terazosin)*

Terazosin Hydrochloride Capsules

5 mg (of terazosin)*

Terazosin Hydrochloride Capsules

10 mg (of terazosin)*

Terazosin Hydrochloride Capsules

AHFS DI Essentials™. © Copyright 2019, Selected Revisions February 13, 2015. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.

† Use is not currently included in the labeling approved by the US Food and Drug Administration.


1. Abbott Laboratories. Hytrin (terazosin hydrochloride) capsules prescribing information. North Chicago, IL; 2001 Feb.

2. Babamoto KS, Hirokawa WT. Doxazosin: a new α1-adrenergic antagonist. Clin Pharm. 1992; 11:415-27.

3. Titmarsh S, Monk JP. Terazosin: a review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in essential hypertension. Drugs. 1987; 33:461-77.

4. Khoury AF, Kaplan NM. α-Blocker therapy of hypertension. JAMA. 1991; 266:394-8.

5. Monda JM, Oesterling JE. Medical treatment of benign prostatic hyperplasia: 5α-reductase inhibitors and α- adrenergic antagonists. Mayo Clin Proc. 1993; 68:670-9.

6. Itskovitz HD. Alpha1 blockers: safe, effective treatment for hypertension. Postgrad Med. 1991; 89:89-112.

7. Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. The fifth report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC V). Arch Intern Med. 1993; 153:154-83.

8. Anon. Terazosin for hypertension. Med Lett Drugs Ther. 1987; 29:112-3.

9. Wilde MI, Fitton A, Sorkin EM. Terazosin: a review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in benign prostatic hypertrophy. Drugs Aging. 1993; 3:258-77.

10. Kyncl JJ. Pharmacology of terazosin. Am J Med. 1986; 80(Suppl 5B):12-9.

11. Deger G. Effect of terazosin on serum lipids. Am J Med. 1986; 80(Suppl 5B):82-5.

12. Deger G. Comparison of the safety and efficacy of once- daily terazosin versus twice-daily prazosin for the treatment of mild to moderate hypertension. Am J Med. 1986; 80(Suppl 5B):62-7.

13. Cohen JD. Long-term efficacy and safety of terazosin alone and in combination with other antihypertensive agents. Am Heart J. 1991; 122:919-25.

14. Ruoff G. Comparative trials of terazosin with other antihypertensive agents. Am J Med. 1986; 80(Suppl 5B):42-8.

15. 1988 Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. The 1988 report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. Arch Intern Med. 1988; 148:1023-38.

16. Weber MA, Laragh JH. Hypertension: steps forward and steps backward. The Joint National Committee fifth report. Arch Intern Med. 1993; 153:149-52.

17. Lepor H, Meretyk S, Knapp-Maloney G. The safety, efficacy and compliance of terazosin therapy for benign prostatic hyperplasia. J Urol. 1992; 147:1554-7.

18. Lepor H. The emerging role of alpha antagonists in the therapy of benign prostatic hyperplasia. J Androl. 1991; 12:389-94.

19. Chapple CR, Christmas TJ, Milroy EJ. A twelve-week placebo-controlled study of prazosin in the treatment of prostatic obstruction. Urol Int. 1990; 45(Suppl 1):47-55.

20. Kirby RS, Coppinger SW, Corcoran MO et al. Prazosin in the treatment of prostatic obstruction. A placebo-controlled study. Br J Urol. 1987; 60:136-42.

21. Chapple C. Medical treatment for benign prostatic hyperplasia. BMJ. 1992; 304:1198-9.

22. Andersson KE. Current concepts in the treatment of disorders of micturition. Drugs. 1988; 35:477-94.

23. Lepor H. Role of long-acting selective alpha-1 blockers in the treatment of benign prostatic hyperplasia. Urol Clin North Am. 1990; 17:651-9.

24. Kirby RS. Alpha-adrenoceptor inhibitors in the treatment of benign prostatic hyperplasia. Am J Med. 1989; 87(Suppl 2A):26-30S.

25. Chisholm GD. Benign prostatic hyperplasia: the best treatment. BMJ. 1989; 299:215-6.

26. Geller J. Nonsurgical treatment of prostatic hyperplasia. Cancer. 1992; 70(Suppl 1):339-45.

27. Garraway WM, Collins GN, Lee RJ. High prevalence of benign prostatic hypertrophy in the community. Lancet. 1991; 338:469-71.

28. Somberg JC. Terazosin: pharmacokinetics and the effect of age and dose on the incidence of adverse events. Am Heart J. 1991; 122:901-5.

29. Jungers P, Ganeval D, Pertuiset N et al. Influence of renal insufficiency on the pharmacokinetics and pharmacodynamics of terazosin. Am J Med. 1986; 80(Suppl 5B):94-9.

30. Sperzel WD, Glassman HN, Jordan DC et al. Overall safety of terazosin as an antihypertensive agent. Am J Med. 1986; 80(Suppl 5B):77-81.

31. Luther RR, Glassman HN, Estep CB et al. The effects of terazosin and methyclothiazide on blood pressure and serum lipids. Am Heart J. 1989; 117:842-7.

32. Holtzman JL, Kaihlanen PM, Rider A et al. Concomitant administration of the terazosin and atenolol for the treatment of essential hypertension. Arch Intern Med. 1988; 148:1539-43.

33. Abbott Laboratories, Abbott Park, IL: Personal communication.

34. National Heart, Lung, and Blood Institute. NHLBI panel reviews safety of calcium channel blockers. Rockville, MD; 1995 Aug 31. Press release.

35. National Heart, Lung, and Blood Institute. New analysis regarding the safety of calcium-channel blockers: a statement for health professionals from the National Heart, Lung, and Blood Institute. Rockville, MD; 1995 Sep 1.

36. Psaty BM, Heckbert SR, Koepsell TD et al. The risk of myocardial infarction associated with antihypertensive drug therapies. JAMA. 1995; 274:620-5.

37. Yusuf S. Calcium antagonists in coronary artery disease and hypertension: time for reevaluation? Circulation. 1995; 92:1079-82. Editorial.

38. Pfizer Roerig. Cardura (doxazosin mesylate) tablets prescribing information. New York, NY; 1994 Dec.

39. Bruskewitz RC. Benign prostatic hyperplasia: drug and nondrug therapies. Geriatrics. 1992; 47:39-45.

40. Oesterling JE. Benign prostatic hyperplasia: medical and minimally invasive treatment options. N Engl J Med. 1995; 332:99-109.

41. Hill SJ, Lawrence SL, Lepor H. New use for alpha blockers: benign prostatic hyperplasia. Am Fam Physician. 1994; 49:1885-8.

42. Roberts RG. Novel idea in BPH guideline: the patient as decision maker. Am Fam Physician. 1994; 49:1044-51.

43. Bostwick DG, Cooner WH, Denis L et al. The association of benign prostatic hyperplasia and cancer of the prostate. Cancer. 1992; 70(Suppl 1):291-301.

44. National Heart, Lung, and Blood Institute National High Blood Pressure Education Program. The sixth report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC VI). Bethesda, MD: National Institutes of Health; 1997 Nov. (NIH publication No. 98-4080.)

45. Kaplan NM. Choice of initail therapy for hypertension. JAMA. 1996; 275:1577-80.

46. Psaty BM, Smith NL, Siscovich DS et al. Health outcomes associated with antihypertensive therapies used as first-line agents: a systematic review and meta-analysis. JAMA. 1997; 277:739-45.

47. Whelton PK, Appel LJ, Espeland MA et al. for the TONE Collaborative Research Group. Sodium reduction and weight loss in the treatment of hypertension in older persons: a randomized controlled trial of nonpharmacologic interventions in the elderly (TONE). JAMA. 1998; 279:839-46.

48. Upjohn Company. Caverject (alprostadil) injection for intracavernosal use prescribing information. Kalamazoo, MI; 1995 Jul.

49. Krane RJ, Goldstein I, Saenz de Tejada I. Impotence. N Engl J Med. 1989; 321:1648-59.

50. The ALLHAT collaborative research group. Major cardiovascular events in hypertensive patients randomized to doxazosin vs chlorthalidone: the Antihypertensive and Lipid-Lowering treatment to prevent Heart Attack Trial (ALLHAT). JAMA. 2000; 283:1967-75.

51. Lasagna L. Diuretics vs α-blockers for treatment of hypertension: lessons from ALLHAT. JAMA. 2000; 283:2013-4.

52. Izzo JL, Levy D, Black HR. Importance of systolic blood pressure in older Americans. Hypertension. 2000; 35:1021-4.

53. Frohlich ED. Recognition of systolic hypertension for hypertension. Hypertension. 2000; 35:1019-20.

54. Bakris GL, Williams M, Dworkin L et al. Preserving renal function in adults with hypertension and diabetes: a consensus approach. Am J Kidney Dis. 2000; 36:646-61.

55. Associated Press (American Diabetes Association). Diabetics urged: drop blood pressure. Chicago, IL; 2000 Aug 29. Press Release from web site.

56. Appel LJ. The verdict from ALLHAT—thiazide diuretics are the preferred initial therapy for hypertension. JAMA. 2002; 288:3039-60.

57. The ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). JAMA. 2002; 288:2981-97.

58. The ALLHAT Officers and Coordinators for the ALLHAT Collaborative Research Group. Major outcomes in moderately hypercholesterolemic, hypertensive patients randomized to pravastatin vs usual care: the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack (ALLHAT). JAMA. 2002; 288:2998-3007.

59. American Urological Association Practice Guideline Committee. AUA guidelines on management of benign prostatic hyperplasia (2003). Chapter 1: Diagnosis and treatment recommendations. J Urol. 2003; 170:530-47.

60. Kaplan NM. Initial treatment of adult patients with essential hypertension. Part 2: alternating monotherapy is the preferred treatment. Pharmacotherapy. 1985; 5:195-200.

61. Bauer JH. Stepped-care approach to the treatment of hypertension: is it obsolete? (unpublished observations)

63. Neal B, MacMahon S, Chapman N. Effects of ACE inhibitors, calcium antagonists, and other blood-pressure-lowering drugs. Lancet. 2000;356:1955-64.

64. Cushman WC, Ford CE, Cutler JA, et al. Success and predictors of blood pressure control in diverse North American settings: The Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT). J Clin Hypertens (Greenwich). 2002;4:393-404.

65. Black HR, Elliott WJ, Neaton JD et al. Baseline characteristics and elderly blood pressure control in the CONVINCE trial. Hypertension. 2001; 37:12-18.

66. Black HR, Elliott WJ, Grandits G, et al. Principal results of the Controlled Onset Verapamil Investigation of Cardiovascular End Points (CONVINCE) trial. JAMA. 2003;289:2073-2082.

67. Dahlof B, Devereux RB, Kjeldsen SE, et al. Cardiovascular morbidity and mortality in the Losartan Intervention For Endpoint Reduction in Hypertension Study (LIFE). Lancet. 2002;359:995-1003.

68. The Heart Outcomes Prevention Evaluation Study Investigators. Effects of an angiotensin-converting-enzyme inhibitor, ramipril, on cardiovascular events in high-risk patients. N Engl J Med. 2000;342:145-153.

69. PROGRESS Collaborative Group. Randomised trial of a perindopril-based blood-pressure-lowering regimen among 6105 individuals with previous stroke or transient ischaemic attack. Lancet. 2001;358:1033-41.

70. Wing LMH, Reid CM, Ryan P, et al, for Second Australian National Blood Pressure Study Group. A comparison of outcomes with angiotensin-converting-enzyme inhibitors and diuretics for hypertension in the elderly. N Engl J Med. 2003;348:583-92.

72. Hunt SA, Baker DW, Chin MH, et al. ACC/AHA guidelines for the evaluation and management of chronic heart failure in the adult. J Am Coll Cardiol. 2001;38:2101-2113.

74. The Guidelines Subcommittee of the WHO/ISH Mild Hypertension Liaison Committee. 1999 guidelines for the management of hypertension. J Hypertension. 1999; 17:392-403.

76. National High Blood Pressure Education Program Working Group on Hypertension Control in Children and Adolescents. The fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents. Pediatrics. 2004; 114(Suppl 2):555-76.

230. American Urological Association Panel Members. American Urological Association guideline: Management of benign prostatic hyperplasia (BPH). Linthicum, MD. 2010. From AUA website.

500. National Heart, Lung, and Blood Institute National High Blood Pressure Education Program. The seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7). Bethesda, MD: National Institutes of Health; 2004 Aug. (NIH publication No. 04-5230.)

501. James PA, Oparil S, Carter BL et al. 2014 evidence-based guideline for the management of high blood pressure in adults: report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA. 2014; 311:507-20.

502. Mancia G, Fagard R, Narkiewicz K et al. 2013 ESH/ESC Guidelines for the management of arterial hypertension: the Task Force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC). J Hypertens. 2013; 31:1281-357.

503. Go AS, Bauman MA, Coleman King SM et al. An effective approach to high blood pressure control: a science advisory from the American Heart Association, the American College of Cardiology, and the Centers for Disease Control and Prevention. Hypertension. 2014; 63:878-85.

504. Weber MA, Schiffrin EL, White WB et al. Clinical practice guidelines for the management of hypertension in the community: a statement by the American Society of Hypertension and the International Society of Hypertension. J Clin Hypertens (Greenwich). 2014; 16:14-26.

a. Sonders RC. Pharmacokinetics of terazosin. Am J Med. 1986; 80:20-24.