What Are The Side Effects Of Terazosin?

Regardless of their formula and intended use, all medications carry a certain risk of side effects. 

Some medications are generally safe to use and the risk of adverse reactions is low, but others are highly likely to cause certain complications. 

If you’ve been prescribed terazosin, you’re probably wondering about its safety profile and whether you may experience side effects. 

The main objective of this post is to explain this topic and discuss the risk of side effects in relation to terazosin use, what to expect, and also shed light on natural alternatives. Read on to get detailed drug information.

What is terazosin?

Terazosin, sold under the brand name Hytrin, belongs to a class of medications called alpha-blockers. Alpha-adrenoreceptors antagonists, also known as alpha-blockers, are medications that reduce blood pressure by preventing the norepinephrine hormone from tightening muscles in the walls of smaller veins and arteries. In turn, blood vessels remain relaxed and open, thus improving blood circulation.

This alpha-blocker was patented back in 1975. Ten years later, in 1985, terazosin came into medical use. The U.S. Food and Drug Administration (FDA) approved terazosin for hypertension treatment in 1987. The approval for improving urination symptoms in men with prostate enlargement came in 1993. 

The numbers show terazosin ranks #203 on the list of the most commonly prescribed medications in the United States, with over 2 million prescriptions.

What is terazosin used for?

Doctors prescribe terazosin to treat hypertension (high blood pressure) and improve lower urinary tract symptoms (LUTS) associated with benign prostatic hyperplasia (BPH) or enlarged prostate. 

In many cases, terazosin is a part of combination therapy which means patients take it with other drugs to prevent heart failure and heart attack or to manage prostate problems.

In the treatment of prostate enlargement, terazosin works by relaxing the smooth muscle of the prostate gland and the bladder neck. As a result, the urinary flow rates increase while decreasing irritative voiding symptoms. 

More precisely, terazosin doesn’t shrink the prostate but acts to relieve bladder outlet obstruction, improve urination, and address other LUTS associated with prostate enlargement. 

Many scientists, including Lepor H, explored the effectiveness of terazosin in treating BPH, but this subject still requires a lot more research. 

Besides high blood pressure and prostate enlargement, terazosin also has some off-label uses. For instance, it has been a subject of research as an off-label medication for medical expulsive therapy (MET). 

Medical expulsive therapy is a treatment option for managing distal ureteral stones. Essentially, ureteral stones are kidney stones that are stuck in one or both ureters, i.e., tubes through which urine flows from the kidneys to your bladder. Larger stones block this urine flow which then may cause pain that many patients describe as severe.

Terazosin is available with a doctor’s prescription only; it’s not an over-the-counter medication. It is important not to diagnose or medicate oneself. Schedule an appointment to see your doctor. 

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Important cautions

While terazosin is prescribed to men and women with hypertension and males with BPH, it’s not for everyone, and some people need to avoid this medication. 

Important warnings associated with terazosin include:

Painful erection warning

Terazosin may cause priapism, a prolonged full or partial erection that lasts for hours and isn’t necessarily caused by sexual stimulation. Priapism can be painful. 

Evidence shows terazosin may induce a painful and long-lasting erection in otherwise healthy men who receive this medication for LUTS. The condition may also affect men with a history of spinal cord injury. 

If you take terazosin and get an abnormal erection (long-lasting and painful), seek medical assistance immediately. Without proper treatment, this problem can cause erectile dysfunction or impotence, i.e., impair erectile function permanently. 

Hypotension warning

This medication can induce a sudden drop in blood pressure, which is particularly noticeable when a person changes position from sitting to standing or from lying to sitting and standing. 

The medical condition where a person experiences dizziness or lightheadedness when changing position is orthostatic hypotension. 

A study from Drugs and Aging confirmed the risk of orthostatic or postural hypotension is higher for alpha-blockers such as terazosin. This type of low blood pressure can happen anytime while taking this medication, but it’s more likely to occur at the beginning of the treatment. 

Cataract surgery warning

People who need to undergo cataract surgery may not be able to take terazosin. The medication can cause intraoperative floppy iris syndrome

The intraoperative floppy iris syndrome (IFIS) is a recently described complication of cataract surgery indicated by weak preoperative pupil dilation accompanied by progressive intraoperative constriction of pupil, flaccid iris stroma billowing, and prolapsed of iris to the surgical incisions. The IFIS was first reported in 2005 and has been strongly associated with BPH and intake of certain medications.

What are the side effects of terazosin?

The reality is that all medications carry a risk of side effects. Some drugs have a low risk of adverse reactions, whereas others are more likely to induce complications. Terazosin can also cause adverse reactions whose severity may vary from one person to another. 

Below, you can learn more about the possible side effects of this medication.

Common terazosin side effects

Some of the most common side effects of taking terazosin include:

  • Dizziness and lightheadedness
  • Urinary tract infection
  • Hypotension (low blood pressure)
  • Increased heart rate
  • Drowsiness
  • Puffiness or swelling in extremities 
  • Nausea
  • Stuffy or runny nose
  • Blurred vision
  • Erectile problems
  • Headache 
  • Asthenia (lack of energy)

In most cases, the abovementioned side effects are considered mild and tend to go away within a few days or several weeks. But, if they are persistent, patients should consult a doctor or pharmacist. 

Serious terazosin side effects

Terazosin capsules can cause serious complications in some cases. Serious adverse reactions of this drug include:

  • Priapism or painful and long-lasting erections
  • Low platelet count
  • Atrial fibrillation (irregular heartbeat)
  • Allergic reaction 

Some people may also experience weight gain, shortness of breath, fainting, and chest pain. In cases of severe adverse effects, patients should contact their healthcare provider. 

Medication interactions

Medication interaction is defined as a change in the action or the side effects of a drug caused by taking another medication or supplement. In other words, medication interactions occur when two or more drugs don’t “get along.” 

Terazosin has several drug interactions, which further cement the fact that this medication is not for everyone with BPH or hypertension. 

The most important medication interactions associated with terazosin include:

  • Erectile dysfunction (ED) medications: combining terazosin with ED drugs such as sildenafil, avanafil, tadalafil, and vardenafil can lower blood pressure and increase the likelihood of fainting, lightheadedness, dizziness, headache, flushing, and nasal congestion.
  • Blood pressure medications: taking terazosin with verapamil, a drug for the treatment of hypertension and angina (chest pain), can cause very low blood pressure. Besides verapamil, terazosin interacts with beta-blocker metoprolol. Terazosin could also interact with medications for pulmonary arterial hypertension. 
  • Other alpha-blockers: terazosin can interact with tamsulosin and prazosin, other alpha-blockers, and thereby increase the risk of side effects. 

Patient transparency is crucial for safety and reduced risk of adverse reactions. Your doctor or urologist needs to know about the medications you’re taking so they can avoid prescribing terazosin if the risk of drug interaction is high. 

Terazosin warnings

This blood pressure medicine comes with several warnings, according to Cerner Multum, you should be aware of. These include:

  • Allergy warning: some people may experience severe allergic reactions indicated by swelling of throat or tongue, and trouble breathing. The allergic reaction requires emergency treatment. Avoid taking terazosin if you are allergic to ingredients in this drug.
  • Risk of falls warning: elderly people, persons with osteoporosis, and individuals with balance problems are at risk of falls. Terazosin is an antihypertensive agent that can lower blood pressure and put you at further risk of falls and injuries. 
  • Hypotension warning: men who take terazosin for BPH and have low blood pressure risk lowering their blood pressure even more. This can then lead to dizziness, lightheadedness, and other symptoms associated with hypotension.
  • Low platelet count warning: some people who take terazosin develop thrombocytopenia (low platelet count). If you already have this problem, terazosin could worsen it. A doctor may order blood tests regularly to monitor platelet count in patients.
  • Warning for seniors: blood-pressure-lowering effects of terazosin are emphasized with postural changes, which increases the risk of falls. The doctor may advise senior patients to take the medication before bedtime.

Women who receive terazosin for high blood pressure may need to avoid it during pregnancy and while breastfeeding. It’s also useful to mention terazosin is not suitable for patients younger than 18 years of age. Consult your health care provider if you have concerns about this medication.

Natural alternatives to terazosin for BPH

Terazosin has the potential to induce a wide range of side effects and thereby make it difficult for patients to have a proper quality of life. If you have an enlarged prostate, there are natural remedies that may safely alleviate symptoms. 

Some of the best natural alternatives to terazosin for BPH management include:

1. Saw palmetto

Saw palmetto is a shrub-like palm tree native to the southeastern U.S. For centuries, people have primarily used this plant’s fruit as a herbal remedy to alleviate urinary symptoms

Many dietary supplements for enlarged prostate contain saw palmetto in their formulas. Studies show saw palmetto is effective in reducing symptoms associated with BPH, and it could also help with chronic prostatitis. 

2. Beta-sitosterol

This is one of many sterols that derive from plants and has a structure like cholesterol produced by the body. Health news evidence confirms beta-sitosterol can alleviate urinary symptoms of BPH, including the urinary flow strength. 

Beta-sitosterol is found in wheat germ, rice bran, corn oils, peanuts, saw palmetto, pygeum, rye grass pollen, and stinging nettle. It’s also possible to find dietary supplements containing beta-sitosterol.

3. Stinging nettle

Also known as common nettle, this plant has been used to relieve symptoms of BPH for centuries. In one study, supplementation with stinging nettle had a more positive impact on symptomatic benign prostatic hyperplasia than placebo. Plus, stinging nettle has a favorable safety profile.

4. Pygeum

Pygeum extract is obtained from the bark of the Prunus africana tree native to Africa. People use the extract to relieve symptoms of an enlarged prostate. Supplementation with pygeum can improve urine flow and bladder emptying, a clinical trial shows.


Terazosin is an alpha-blocker prescribed for the treatment of hypertension and enlarged prostate. This medication causes a wide range of side effects that affect a patient’s quality of life. Talk to your healthcare provider if you’re concerned about the side effects you’re experiencing.

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  1. Yang CH, Raja A. Terazosin. [Updated 2021 Jul 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022. https://www.ncbi.nlm.nih.gov/books/NBK545208/
  2. Sadeghi-Nejad H, Jackson I. New-onset priapism associated with ingestion of terazosin in an otherwise healthy man. J Sex Med. 2007. https://pubmed.ncbi.nlm.nih.gov/17451488/
  3. Rivasi G, Rafanelli M, Mossello E, Brignole M, Ungar A. Drug-Related Orthostatic Hypotension: Beyond Anti-Hypertensive Medications. Drugs Aging. 2020. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7524811/
  4. Venkatesh R, Veena K, Gupta S, Ravindran RD. Intraoperative floppy iris syndrome associated with terazosin. Indian J Ophthalmol. 2007. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2636019/
  5. Gordon AE, Shaughnessy AF. Saw palmetto for prostate disorders. Am Fam Physician. 2003. https://pubmed.ncbi.nlm.nih.gov/12674456/
  6. Penugonda K, Lindshield BL. Fatty acid and phytosterol content of commercial saw palmetto supplements. Nutrients. 2013;5(9):3617-3633. Published 2013 Sep 13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3798925/
  7. Ghorbanibirgani A, Khalili A, Zamani L. The efficacy of stinging nettle (urtica dioica) in patients with benign prostatic hyperplasia: a randomized double-blind study in 100 patients. Iran Red Crescent Med J. 2013. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3589769/
  8. Keehn A, Lowe FC. Complementary and alternative medications for benign prostatic hyperplasia. Can J Urol. 2015. https://pubmed.ncbi.nlm.nih.gov/26497340/

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