Based on NIH | Is dizziness a common side effect of Losartan, and what should I do if it happens after taking my dose?

Overview

Yes, dizziness is a recognized side effect of losartan (an angiotensin II receptor blocker used for blood pressure and certain heart/kidney conditions), and it tends to be more noticeable when starting the medication, after a dose change, or when standing up quickly. If dizziness occurs, you can often manage it at home with simple steps, but certain warning signs mean you should contact a clinician promptly. ^{[1] [2]}

---

Why Losartan Can Cause Dizziness

• Lower blood pressure effects: Losartan can lower blood pressure enough to cause lightheadedness or a faint feeling, especially with posture changes (standing up suddenly), a phenomenon often called orthostatic hypotension. This is more likely early in treatment or in those also taking diuretics (“water pills”). ^{[3] [4]}
• Sensitivity in some individuals: Older adults or those with dehydration (from vomiting, diarrhea, or not drinking enough fluids) may feel dizzy more easily because blood pressure drops more readily. Elderly people can be more sensitive to these effects. ^{[5] [6]}

---

How Common Is Dizziness with Losartan?

• In controlled clinical trials, dizziness was reported among the more frequent adverse experiences with losartan. Only dizziness was more often considered drug-related with losartan than with placebo (about 2.4% vs 1.3%). ^[7]
• Another large trial summary also identified dizziness among common side effects, with first‑dose hypotension described as rare. Overall tolerability of losartan is favorable compared with several other blood pressure medicines. ^[8]

---

Immediate Steps If You Feel Dizzy After Your Dose

• Lie down right away. If you feel faint or dizzy, lie down so you don’t fall; once the sensation eases, sit for a few moments before standing to reduce the chance it comes back. ^[3]
• Stand up slowly. Rising gradually from sitting or lying helps prevent a sudden drop in blood pressure and recurrence of dizziness. ^[6]
• Avoid driving or operating machinery until you know how you respond to losartan and the dizziness has resolved. ^{[3] [9]}
• Hydrate appropriately. If you’ve had vomiting, diarrhea, or heavy sweating, ensure adequate fluids; dehydration can worsen blood pressure drops and dizziness. ^[6]

---

When to Call Your Clinician

• If you faint at any time, contact your clinician right away. Fainting suggests blood pressure may be too low or that other issues need evaluation. ^[3]
• Persistent or severe dizziness, especially if it starts after a dose increase or when combined with other blood pressure‑lowering drugs, warrants medical advice about dose adjustment or timing. ^[4]
• New swelling in feet/ankles/hands or unexplained weight gain should be reported, as losartan can affect kidney function in susceptible individuals. ^[1]
• Signs of an allergic reaction (swelling of face, lips, tongue, or throat) require emergency care and stopping the medicine. ^[2]

---

Practical Prevention Tips

• Take your dose at a consistent time, and consider taking it in the evening if daytime lightheadedness is bothersome; discuss timing changes with your clinician to ensure it fits your blood pressure plan. ^[4]
• Check blood pressure at home if possible, especially when starting or changing doses; record readings and symptoms to share with your clinician. First‑dose hypotension is uncommon, but monitoring helps identify low readings early. ^[8]
• Limit alcohol and sedatives, which can intensify lightheadedness or orthostatic symptoms. ^[10]
• Be cautious with other medicines that lower blood pressure or increase potassium; diuretics can amplify dizziness, and some combinations may need dose adjustments. ^{[4] [11]}
• Rise slowly from bed in the morning: sit with feet on the floor for a minute before standing. This simple routine can reduce morning lightheadedness. ^[6]

---

Special Considerations

• Older adults: Start doses are often kept conservative, and extra care with posture changes and hydration can help minimize dizziness. Elderly individuals tend to be more sensitive to blood pressure shifts. ^[5]
• Concurrent diuretics (e.g., hydrochlorothiazide): Combination therapies like losartan/HCTZ can be effective but may increase the chance of dizziness due to additive effects on blood pressure; the advice to lie down with dizziness and call your clinician if fainting occurs applies equally here. ^{[12] [13]}

---

Summary Table: Dizziness and What to Do

Topic	Key Points	Action Steps
Is dizziness common?	Dizziness is a known side effect; more often considered drug-related in losartan vs placebo. [7] [8]	Expect possible lightheadedness when starting or with dose changes.
Why it happens	Blood pressure lowering and postural changes can cause lightheadedness/faintness. [3] [4]	Stand up slowly; monitor for patterns.
Immediate response	Lie down; sit before standing; avoid driving if dizzy. [3] [9]	Prioritize safety; prevent falls.
Call clinician if…	You faint; dizziness is persistent/severe; swelling or weight gain occurs. [3] [1]	Seek prompt medical guidance.
Prevention tips	Hydrate; limit alcohol/sedatives; consider dose timing; monitor BP at home. [6] [10] [8]	Adjust routine; share readings and symptoms with clinician.
Higher‑risk groups	Elderly, dehydrated, and those on diuretics may be more sensitive. [5] [4]	Extra caution with posture and fluids; review meds.

---

Bottom Line

Dizziness can occur with losartan and is usually related to lowered blood pressure or standing up quickly. If you feel dizzy, lie down, rise slowly, and avoid driving until it passes; contact your clinician urgently if you faint or if dizziness persists or worsens. ^{[3] [9] [4]}