Based on NIH | Is blurred vision a known side effect of Losartan, and when should I seek medical attention if I experience it?

Blurred vision can occur with Losartan, though it appears to be uncommon. The official prescribing information for Losartan lists “blurred vision” among reported side effects, typically under “special senses,” which means some users have experienced it. ^{[1] [2]} In combination products that include Losartan with hydrochlorothiazide (HCTZ), blurred vision is also listed among reported side effects. ^{[3] [4] [5]}

Why it happens

• Blood pressure changes: Starting or adjusting blood pressure medication can temporarily shift eye perfusion and cause lightheadedness or visual blurring in some people; dizziness is one of the more common drug‑related effects reported with Losartan, which may accompany brief visual changes. ^[6]
• Eye-specific effects from HCTZ combos: If you take a Losartan/HCTZ combination, there is a rare but serious eye problem called acute angle‑closure glaucoma that can occur within hours to weeks of starting therapy, causing decreased vision and/or eye pain. This needs urgent evaluation because untreated cases can lead to permanent vision loss. ^{[7] [8] [9]}

When to seek medical attention

• Get urgent care now (same day or emergency) if you have any of the following:
  • Sudden decrease in vision, eye pain, halos around lights, redness, headache, nausea/vomiting, or a rapid worsening of blurred vision, especially within the first hours to weeks after starting a Losartan/HCTZ product. These can be signs of acute angle‑closure glaucoma and require prompt treatment. ^{[7] [8]}
• Contact your prescriber promptly (within 24–48 hours) if you notice new or persistent blurred vision without pain while on Losartan alone or Losartan/HCTZ, even if mild, so they can assess dose, drug interactions, and alternative causes. Blurred vision is listed among reported side effects for both Losartan and Losartan/HCTZ. ^{[1] [3]}

What to do right away

• Do not stop Losartan on your own unless you’re told to by a clinician, because stopping suddenly may allow blood pressure to rise. However, if you have symptoms suggesting acute angle‑closure glaucoma (decreased vision plus eye pain) while taking a Losartan/HCTZ product, discontinuation of HCTZ is part of the initial management and you should seek urgent care immediately. ^{[7] [8]}
• Monitor your blood pressure during symptoms and note readings to share with your clinician, as large swings can contribute to visual changes.
• Consider an eye exam if symptoms persist; guidance recommends ophthalmology evaluation when vision changes occur during treatment with Losartan/HCTZ. ^[10]

How common is it?

Large clinical programs show Losartan is generally well tolerated, with dizziness more commonly reported than placebo and few discontinuations due to side effects. While blurred vision is specifically listed in official labeling, the exact frequency appears low compared with common effects like dizziness. ^{[6] [1]}

Special considerations

• Combination with diuretics (HCTZ): The risk of acute angle‑closure glaucoma, while rare, is specifically linked to the HCTZ component in some individuals and can present soon after starting therapy. Symptoms include decreased visual acuity and eye pain and warrant rapid evaluation. ^{[7] [8]}
• Other red flags: If blurred vision occurs with facial or tongue swelling or breathing difficulty, that could suggest an allergic reaction; though more classically associated with ACE inhibitors, severe reactions have been reported with agents in the renin–angiotensin system and should prompt urgent care. ^[11]

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Quick reference table

Situation	What it may indicate	What to do
Mild, intermittent blurred vision without pain after starting Losartan	Possible transient side effect or blood pressure adjustment	Monitor symptoms and blood pressure; contact your prescriber within 24–48 hours for guidance. [1] [6]
Blurred vision plus eye pain, sudden decrease in vision, halos, headache, nausea, within hours–weeks of starting Losartan/HCTZ	Possible acute angle‑closure glaucoma (rare but serious)	Seek urgent medical care immediately; HCTZ may need to be stopped promptly under medical supervision. [7] [8]
Persistent blurred vision even without pain	Ocular surface issues, refractive change, medication effect, or other eye disease	Arrange timely appointment with your prescriber and consider ophthalmology evaluation. [10]
Blurred vision with swelling of face/lips/tongue or breathing trouble	Possible hypersensitivity reaction	Emergency care immediately. [11]

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Bottom line

• Yes blurred vision is a known but uncommon side effect of Losartan and of Losartan/HCTZ. ^{[1] [3]}
• If you experience blurred vision with eye pain or a sudden drop in vision especially soon after starting a product that includes HCTZ seek urgent care due to the risk of acute angle‑closure glaucoma. ^{[7] [8]}
• For mild, painless blurring, contact your clinician promptly to review your medications, blood pressure, and whether an eye exam is needed. ^[10]