Based on NIH | Is frequent urination a known side effect of losartan, and when should I contact my doctor if I notice increased urination after starting it?

Overview

Frequent urination (urinary frequency or nocturia) can occur with losartan, although it’s not among the most common side effects. In official product information for losartan, urinary frequency and nocturia are listed among reported urogenital adverse events. ^[1] Similar listings appear for branded losartan tablets, noting urinary frequency and nocturia as possible side effects. ^[2] Combination tablets that include losartan with hydrochlorothiazide also list urinary frequency and nocturia among reported adverse experiences, and the diuretic component (hydrochlorothiazide) can increase urine output. ^{[3] [4]}

---

How Common Is It?

Losartan alone is generally well tolerated, and most adverse effects occur at rates similar to placebo in clinical trials. Dizziness is the only adverse effect consistently reported more often than placebo, while urinary symptoms are reported but not highlighted as common. ^[5] Broad safety reviews show losartan’s overall adverse-event profile comparable to placebo, without a prominent signal for urinary frequency; however, urinary frequency and nocturia do appear in adverse-event listings. ^[6] This means increased urination is possible, but not typically frequent or severe in most users. ^{[1] [2]}

---

Why Might Urination Increase?

• Losartan’s class effect on the kidney can modestly increase urinary sodium excretion, which may slightly change urine patterns for some people. ^[7] It also increases uric acid excretion, which doesn’t directly cause frequent urination but reflects changes in kidney handling of solutes. ^[7]
• If you are taking a combination pill with hydrochlorothiazide (often labeled “HCTZ”), the diuretic component is designed to increase urine output, which commonly leads to more frequent urination, especially in the first weeks. ^{[3] [4]}

---

When to Contact Your Doctor

You don’t need to seek urgent care for mild, short-lived increases in urination that settle within a couple of weeks as your body adjusts. However, you should contact your doctor if increased urination is persistent, bothersome, or accompanied by warning signs such as decreased urine output, swelling, unexplained weight gain, or signs of a urinary tract infection. ^[8] Urinary tract infection is a listed adverse event; if frequent urination is paired with burning, urgency, fever, or cloudy urine, let your doctor know. ^[1] If you’re on losartan/HCTZ and notice symptoms of dehydration (excessive thirst, dizziness, very dark urine) or a marked change in the frequency or amount of urine, you should reach out promptly. ^[9]

Consider contacting your doctor sooner if:

• You have kidney disease and notice worsening swelling, rising weight, or reduced urine output. ^[8]
• Your urination changes are severe or sudden, especially alongside lightheadedness or low blood pressure symptoms. ^[8]
• You suspect a urinary tract infection (painful urination, urgency, fever). ^[1]

---

Practical Tips

• Track your fluid intake and timing; drinking later in the evening can worsen nocturia, and shifting fluids earlier may help.
• If you’re on losartan/HCTZ, expect an increase in urination; taking the dose in the morning can reduce nighttime trips. ^[3]
• Avoid excess alcohol and review caffeine intake, as both can affect urinary frequency.
• Report persistent or worsening symptoms to your clinician; dose timing or medication choice can often be adjusted.

---

Key Takeaways

• Frequent urination and nocturia are recognized but not common side effects of losartan. ^{[1] [2]}
• Losartan/HCTZ combinations more often cause increased urination due to the diuretic component. ^{[3] [4]}
• Contact your doctor if increased urination is persistent, bothersome, or coupled with signs of kidney issues or urinary infection. ^{[8] [9] [1]}