Based on NIH | Can losartan cause muscle pain or cramps, and how common is this side effect?

Overview

Losartan (brand name Cozaar) can be associated with muscle-related symptoms such as muscle cramps, leg pain, back pain, and muscular weakness, but these effects appear to be uncommon and often occur at rates similar to placebo in clinical trials. ^[1] In large, controlled studies, dizziness was the only adverse effect consistently higher than placebo, while most musculoskeletal complaints were reported at low frequencies (around 1% or less for “muscle cramp” in pivotal trials). ^{[2] [1]}

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What muscle symptoms have been reported?

• Muscle cramps: Reported at approximately 1% in losartan-treated participants in controlled trials. ^[1]
• Leg pain and back pain: Recorded at about 1–2% in clinical datasets. ^[1]
• Muscular weakness: Listed among musculoskeletal adverse events in labeling, though typically low incidence and comparable to placebo in many trial summaries. ^[3]

These events were generally infrequent and not consistently higher than placebo across studies, suggesting a relatively low likelihood that losartan alone causes muscle pain or cramps for most users. ^{[1] [2]}

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How common is it?

Evidence from double‑blind trials evaluating roughly 3,700 people with hypertension shows overall adverse event rates similar to placebo, with dizziness being the only patient‑reported event clearly exceeding placebo (about 2.4% vs 1.3%). ^[2] Within the musculoskeletal category, muscle cramps were about 1% and leg/back pain around 1–2% in core trial tables for losartan. ^[1] In extended adverse event listings, musculoskeletal complaints appear at low single‑digit percentages and are often comparable to placebo. ^[3]

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Important distinction: Losartan alone vs. combination pills

Combination products that include a diuretic (such as losartan with hydrochlorothiazide) list muscle cramps and muscle weakness more prominently, which may reflect the diuretic component’s effects on electrolytes (like potassium or sodium) rather than losartan itself. ^{[4] [5]} If you are on a losartan‑diuretic combination and develop cramps, electrolyte shifts could be a contributing factor. ^{[4] [5]}

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Practical guidance

• If you notice new muscle cramps or pain: It could be incidental, related to activity, hydration, or electrolyte balance, and not necessarily due to losartan, given the low observed rates and placebo‑like profile. ^{[2] [1]}
• Check for contributing factors: Dehydration, low sodium, or other medications (especially diuretics) can increase the chance of cramps. Combination tablets with a diuretic list muscle cramps more often. ^{[4] [5]}
• When to seek help: Persistent, worsening, or severe muscle pain or weakness deserves medical review to assess electrolytes and consider alternative causes. While losartan’s risk appears low, a personalized evaluation is helpful. ^{[2] [3]}

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Key data at a glance

Adverse event (musculoskeletal)	Approximate incidence with losartan in trials	Notes
Muscle cramp	~1%	Reported in controlled trial tables; generally low and similar to placebo. [1]
Leg pain	~1%	Low incidence in labeling tables. [1]
Back pain	~2%	Low incidence; not consistently higher than placebo. [1]
Muscular weakness	Listed (single‑digit %)	Appears in extended labeling; typically low frequency. [3]
Overall adverse events vs placebo	Similar	Dizziness was notably higher than placebo; musculoskeletal symptoms generally low. [2]

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Bottom line

• Yes, losartan can be linked to muscle cramps or pain, but these events are uncommon and often occur at rates similar to placebo. ^{[1] [2]}
• Combination tablets with hydrochlorothiazide may show muscle cramps more prominently, likely due to electrolyte effects from the diuretic component. ^{[4] [5]}
• If muscle symptoms arise, consider hydration, electrolyte status, and other medicines; seek evaluation if symptoms are persistent or severe. ^{[2] [3]}