How long does losartan take to lower blood pressure?

Losartan starts working within a few hours, but it takes 3 to 6 weeks to reach its full blood-pressure-lowering effect. Your doctor will likely wait at least 3 to 4 weeks before considering a dose change.

Can I eat bananas while taking losartan?

You can eat bananas in normal amounts. However, because losartan can raise potassium levels, avoid excessive consumption of high-potassium foods and do not use potassium-based salt substitutes without asking your doctor.

Is losartan safer than lisinopril?

Both are effective blood pressure medications. Losartan (an ARB) is less likely to cause the dry cough associated with lisinopril (an ACE inhibitor). Otherwise, both have similar safety profiles. Your doctor will choose based on your specific health needs.

Can I take ibuprofen with losartan?

Occasional use of ibuprofen is usually fine, but regular use of NSAIDs like ibuprofen can reduce losartan effectiveness and may harm your kidneys. Acetaminophen (Tylenol) is generally a safer pain reliever while on losartan. Always check with your doctor.

What to Expect When Starting Losartan

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Introduction

Losartan is an angiotensin II receptor blocker (ARB) used to treat high blood pressure, protect the kidneys in people with type 2 diabetes, and reduce the risk of stroke in certain patients. It works by blocking a chemical that causes blood vessels to tighten, allowing them to relax and lower blood pressure.

Starting a new blood pressure medication can feel like a big step. Losartan is generally well tolerated, with fewer side effects than some older blood pressure medications. Most people adjust to it within the first few weeks without significant problems.

Your doctor will likely start you on a dose of 25 to 50 mg once daily. The full blood-pressure-lowering effect develops over 3 to 6 weeks, so patience is important during the early adjustment period.

Week-by-week timeline

Days 1-3Dizziness is more likely if you are also taking a diuretic or are dehydrated. Rise slowly from sitting or lying positions.

Getting Started

You begin taking losartan once daily. Blood pressure may start to decrease slightly. Your body is beginning to adjust to the change in how your blood vessels function.

Possible mild dizziness, especially when standing up quickly
Slight fatigue
Most people feel no different
No immediate dramatic change in blood pressure

Week 1-2Unlike ACE inhibitors, losartan rarely causes a persistent dry cough. If you switched from an ACE inhibitor for this reason, you should notice improvement.

Early Adjustment

Blood pressure is beginning to respond to the medication. Some people notice upper respiratory symptoms, which are a known side effect of ARBs.

Mild dizziness improving
Occasional stuffy nose or sinus congestion
Possible mild back pain or muscle aches
Blood pressure trending downward

Weeks 3-6Your doctor may order blood tests to check your potassium and creatinine levels, as ARBs can affect kidney function and potassium balance.

Reaching Full Effect

Losartan achieves its maximum blood-pressure-lowering effect over 3 to 6 weeks. Your doctor may check your blood pressure and kidney function during this period.

Blood pressure readings closer to target
Most initial side effects resolved
Blood work to check kidney function and potassium levels
Routine established

Weeks 6-12If your blood pressure is not at goal on losartan alone, adding a low-dose diuretic like hydrochlorothiazide is a common and effective strategy.

Dose Optimization

Your doctor may adjust your dose based on your blood pressure response. Losartan can be increased to 100 mg daily or combined with other medications if needed.

Stable blood pressure control
Possible dose adjustment
Potential addition of a second medication if BP is not at goal
Feeling well-adjusted to the medication

Months 3+Do not stop losartan without consulting your doctor. Sudden discontinuation can cause a rebound increase in blood pressure.

Long-Term Therapy

Losartan is a long-term medication that provides ongoing cardiovascular and kidney protection. Consistent daily use is important for maintaining benefits.

Stable blood pressure
Regular monitoring visits
Minimal or no side effects
Continued kidney protection in diabetic patients

When to call your doctor

Contact your healthcare provider if you experience:

Swelling of the face, lips, tongue, or throat (angioedema — rare but serious)
Feeling faint or lightheaded, especially after the first dose
Significant decrease in urine output
Unexplained muscle weakness or irregular heartbeat (possible high potassium)
Signs of allergic reaction: severe rash, itching, or difficulty breathing
Dark urine or yellowing of the skin/eyes

Tips for getting started

Take losartan at the same time every day, with or without food. If you are also taking a diuretic, make sure you stay well hydrated, especially during hot weather or exercise, to prevent excessive blood pressure drops.

Avoid potassium supplements and potassium-rich salt substitutes unless your doctor approves them, as losartan can raise potassium levels. Also avoid NSAIDs (like ibuprofen) when possible, as they can reduce the effectiveness of losartan and affect your kidneys.

Keep all follow-up appointments so your doctor can monitor your blood pressure, kidney function, and electrolytes. Home blood pressure monitoring is helpful — measure at the same time each day, sit quietly for 5 minutes first, and keep a record to share with your doctor.

Frequently asked questions

More about Losartan

Losartan drug guideSide effects, dosage, interactions, and more Lisinopril vs LosartanCompare these medications Losartan vs AmlodipineCompare these medications Losartan vs ValsartanCompare these medications Lisinopril & LosartanInteraction details Losartan & HydrochlorothiazideInteraction details Losartan & MetoprololInteraction details

References

[Observational] Losartan Drug Label https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5e4b75c8-c595-47a4-84e6-8a0c3d65ac4b Accessed 2026-03-01.
[Observational] Losartan Monograph https://medlineplus.gov/druginfo/meds/a695008.html Accessed 2026-03-01.
[Observational] Angiotensin Receptor Blockers https://www.ncbi.nlm.nih.gov/books/NBK537027/ Accessed 2026-03-01.
[Observational] LIFE Study: Losartan for Stroke Prevention https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(02)08915-X/fulltext Accessed 2026-03-01.

Written and fact-checked by PrescriptionDrugs.org Editorial Team

Last updated: March 1, 2026