What are the side effects of Terazosin (Hytrin)?

From the Guidelines

Terazosin can cause several side effects, including dizziness, lightheadedness, and drowsiness, especially when standing up quickly, due to its mechanism of blocking alpha-1 receptors, which can lead to orthostatic hypotension, as noted in the 2018 guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.

Common Side Effects

• Dizziness
• Lightheadedness
• Drowsiness
• Headache
• Weakness
• Fatigue
• Nasal congestion
• Swelling in the hands, feet, or ankles (peripheral edema)

Less Common but More Serious Side Effects

• Fainting
• Irregular heartbeat
• Priapism (prolonged, painful erection)

Sexual Side Effects

• Decreased libido
• Erectile dysfunction

Minimizing Side Effects

To minimize these effects, terazosin is usually started at a low dose (1 mg) at bedtime and gradually increased as needed, as recommended in the guideline 1. The first-dose effect, where blood pressure drops significantly after the initial dose, can be particularly pronounced, so patients should take their first dose at bedtime and avoid driving or operating machinery until they know how the medication affects them. Patients should rise slowly from sitting or lying positions and stay well-hydrated.

Mechanism of Action

These side effects occur because terazosin blocks alpha-1 receptors, causing blood vessels to relax and widen, which lowers blood pressure but can lead to these unwanted effects, as explained in the guideline 1.

Dosage and Administration

The usual dose range for terazosin is 1-20 mg, taken once or twice daily, as listed in the guideline 1.

Special Considerations

Patients with concomitant benign prostatic hyperplasia (BPH) may be considered for terazosin as a second-line agent, as noted in the guideline 1.

From the FDA Drug Label

ADVERSE REACTIONS Benign Prostatic Hyperplasia The incidence of treatment-emergent adverse events has been ascertained from clinical trials conducted worldwide. Table 1 summarizes those adverse events reported for patients in these trials when the incidence rate in the terazosin group was at least 1% and was greater than that for the placebo group, or where the reaction is of clinical interest. Asthenia, postural hypotension, dizziness, somnolence, nasal congestion/rhinitis, and impotence were the only events that were significantly (p </= 0. 05) more common in patients receiving terazosin than in patients receiving placebo. Table 1 Adverse Reactions During Placebo-controlled Trials Benign Prostatic Hyperplasia Body System Terazosin (N = 636) Placebo (N = 360) BODY AS A WHOLE †Asthenia 7.4%* 3.3% Flu Syndrome 2.4% 1.7% Headache 4.9% 5.8% CARDIOVASCULAR SYSTEM Hypotension 0.6% 0.6% Palpitations 0.9% 1.1% Postural Hypotension 3.9%* 0. 8% Syncope 0.6% 0.0% DIGESTIVE SYSTEM Nausea 1.7% 1.1% METABOLIC AND NUTRITIONAL DISORDERS Peripheral Edema 0.9% 0.3% Weight Gain 0.5% 0.0% NERVOUS SYSTEM Dizziness 9.1%* 4.2% Somnolence 3.6%* 1.9% Vertigo 1.4% 0.3% RESPIRATORY SYSTEM Dyspnea 1.7% 0.8% Nasal Congestion/Rhinitis 1.9%* 0.0% SPECIAL SENSES Blurred Vision/Amblyopia 1.3% 0.6% UROGENITAL SYSTEM Impotence 1.6%* 0. 6% Urinary Tract Infection 1.3% 3. 9%*

The side effects of Terazosin (Hytrin) include:

• Asthenia (7.4%)
• Postural hypotension (3.9%)
• Dizziness (9.1%)
• Somnolence (3.6%)
• Nasal congestion/rhinitis (1.9%)
• Impotence (1.6%)
• Hypotension (0.6%)
• Palpitations (0.9%)
• Syncope (0.6%)
• Nausea (1.7%)
• Peripheral edema (0.9%)
• Weight gain (0.5%)
• Vertigo (1.4%)
• Dyspnea (1.7%)
• Blurred vision/amblyopia (1.3%)
• Urinary tract infection (1.3%) 2 Other side effects that could occur while taking Terazosin Capsules include:
• Drowsiness
• Blurred or hazy vision
• Nausea
• Puffiness of the feet or hands
• Prolonged abnormal erection 2

From the Research

Side Effects of Terazosin (Hytrin)

The side effects of Terazosin (Hytrin) are well-documented in various studies. Some of the most common side effects include:

• Dizziness 3, 4, 5, 6
• Headache 3
• Asthenia (weakness or lack of energy) 3, 6
• Nasal congestion 3
• Postural hypotension (low blood pressure when standing up) 4, 6
• Drowsiness 4
• Dry mouth 5
• Syncope (fainting) 3, 7, 6

Less Common Side Effects

Some less common side effects of Terazosin (Hytrin) include:

• Persistent dizziness 4
• Orthostatic blood pressure change 6
• Postural symptoms 6

Factors Affecting Side Effects

The incidence of side effects may be affected by various factors, including:

• Age: The pharmacokinetics of Terazosin are not significantly affected by age 7
• Dose: The incidence of adverse events may be related to the dose of Terazosin 7, 6
• Blood pressure: Changes in systolic blood pressure may be associated with the incidence of treatment-related adverse events 6