Skip to main content

Prazosin Disease Interactions

There are 2 disease interactions with prazosin.


Alpha-1 blockers (applies to prazosin) hypotension

Moderate Potential Hazard, High plausibility. Applicable conditions: Syncope, Autonomic Neuropathy, Dehydration, Diarrhea, Vomiting

Peripheral alpha 1- adrenergic receptor blocking agents (aka alpha 1- blockers) cause vasodilation and can produce marked hypotension, especially orthostatic hypotension with syncope or other postural symptoms such as dizziness, lightheadedness, and palpitations. Orthostatic effects are most common during initiation of therapy and often occur within 90 minutes after the first dose. However, they can also occur following a dosage increase or resumption of therapy after an interruption of more than a few days. Agents with alpha 1a specificity, such as tamsulosin, act primarily on the prostate but are not devoid of hypotensive effects. Therapy with peripheral alpha-1 blockers should be administered cautiously in patients with or predisposed to hypotensive or syncopal episodes. Caution is also advised in patients who are dehydrated (e.g., due to severe or prolonged diarrhea or vomiting), since they may be more sensitive to the hypotensive effect of the drugs. Therapy should be initiated with the lowest dosage possible and titrated gradually based on patient response and tolerance in accordance with the individual product package labeling. During initiation or reinstitution of therapy and following an increase in dosage, patients should be advised not to rise abruptly from a sitting or recumbent position and to avoid situations where injury could result if syncope occur. Concomitant use of alcohol, extensive periods of standing, prolonged or intense exercise, and exposure to heat can also precipitate orthostatic hypotension and should be minimized. If dizziness, lightheadedness or palpitations occur, the patient should sit or lie down, and seek medical attention if symptoms are recurrent or bothersome.


  1. Grunstein JA "The problem of postural hypotension." Gerontol Clin (Basel) 16 (1974): 171-4
  2. Glass AR, Ballou R "Pheochromocytoma, prazosin, and hypotension." Ann Intern Med 97 (1982): 455
  3. Melkild A "Prazosin (peripress): a long-term study." Curr Med Res Opin 9 (1984): 219-28
  4. Graham RM, Thornell IR, Gain JM, Bagnoli C, Oates HF, Stokes GS "Prazosin: the first-dose phenomenon." Br Med J 2 (1976): 1293-4
  5. "Prazosin (Minipress) for hypertension." Med Lett Drugs Ther 19 (1977): 1-2
  6. Salim SS, Mtui EP, Makene WJ "An open evaluation of the efficacy and toleration of prazosin in patients with hypertension." East Afr Med J 54 (1977): 429-33
  7. "Product Information. Cardura (doxazosin)." Pfizer U.S. Pharmaceuticals PROD (2001):
  8. "Product Information. Hytrin (terazosin)." Abbott Pharmaceutical PROD (2001):
  9. Troffa C, Manunta P, Dessifulgheri P, Pazzola A, Sabino G, Patteri G, Tonolo G, Pupita G, Glorioso N, Gitti M, Rappelli A "Efficacy and tolerability of doxazosin alone or in combination with chlorthalidone in essential hypertension." Curr Ther Res Clin Exp 55 (1994): 22-31
  10. Ahaneku JE, Taylor OG, Walker D, Agbedana OE, Salako LA "Blood pressure and biochemical changes during doxazosin monotherapy in nigerian hypertensive patients." Curr Ther Res Clin Exp 55 (1994): 1067-74
  11. Takata Y, Yoshizumi T, Ito Y, Hirota Y, Fujishima M "Effect of administration and withdrawal of doxazosin on ambulatory blood pressure in patients with essential hypertension." Angiology 46 (1995): 11-8
  12. Limbird LE eds., Gilman AG, Hardman JG "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: McGraw-Hill (1995):
  13. Roehrborn CG, Siegel RL "Safety and efficacy of doxazosin in benign prostatic hyperplasia: a pooled analysis of three double-blind, placebo-controlled studies." Urology 48 (1996): 406-15
  14. "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim PROD (2001):
  15. "Product Information. Uroxatral (alfuzosin)." sanofi-aventis (2003):
  16. "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals (2008):
View all 16 references

Prazosin (applies to prazosin) liver disease

Moderate Potential Hazard, High plausibility. Applicable conditions: Biliary Obstruction

Little data exist concerning the pharmacokinetic disposition of prazosin in patients with liver disease. Prazosin is known to be metabolized by the liver and subsequently excreted in the bile, primarily as metabolites. Some of the metabolites are pharmacologically active and possess 10% to 25% of the hypotensive activity of prazosin. Therapy with prazosin should be administered cautiously in patients with significantly impaired hepatic or biliary function, since drug and/or metabolite accumulation may occur.


  1. Bateman DN, Rawlins MD "Prazosin concentration-effect, metabolism and biological activity of metabolites." Br J Clin Pharmacol 11 (1981): 221-

Prazosin drug interactions

There are 261 drug interactions with prazosin.

Prazosin alcohol/food interactions

There is 1 alcohol/food interaction with prazosin.

Report options

QR code containing a link to this page

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.