Educational use only. Drug cards are AI-assisted study material for NCLEX preparation.
Mechanism of action
Selectively blocks the angiotensin II type-1 (AT1) receptor, preventing vasoconstriction and aldosterone release. Hemodynamic effect is similar to ACE inhibitors but losartan does not raise bradykinin — so the dry cough and angioedema risks are much lower. Used for hypertension, heart failure, and diabetic nephropathy.
Adverse effects
Life-threatening / NCLEX-tested
- Angioedema (rare, but possible — especially if there is a prior ACE-inhibitor angioedema history)
- First-dose hypotension, particularly in volume-depleted patients
- Hyperkalemia
- Acute kidney injury, especially with bilateral renal artery stenosis
- Teratogenic — contraindicated in pregnancy at any trimester
Side effects
Common — what to teach
- Dizziness, lightheadedness
- Headache
- Fatigue
- Cough is uncommon (key clinical advantage over ACE inhibitors)
- Mild upper respiratory symptoms
Food & drug interactions
Potassium-sparing diuretics (spironolactone), potassium supplements, and salt substitutes compound hyperkalemia. NSAIDs blunt the antihypertensive effect and worsen renal function. Lithium clearance falls. Combining with an ACE inhibitor or aliskiren ("dual RAAS blockade") is contraindicated. Alcohol amplifies hypotension.
Nursing implications
Assessment, monitoring, patient teaching
- Check BP and pulse before each dose; counsel patients to rise slowly
- Monitor K+, BUN, and creatinine at baseline, 1–2 weeks after start or dose change, then periodically
- Teach patients to report face/lip/tongue swelling — angioedema is rare but real
- Avoid potassium-rich salt substitutes and review supplement use
- Common reason for switch from an ACE inhibitor — losartan eliminates the dry cough
- Pregnancy test before starting in women of childbearing age
When to hold / contraindications
- SBP < 90 mmHg or symptomatic hypotension
- Serum K+ > 5.0 mEq/L
- Rising creatinine > 30% from baseline
- Any sign of angioedema — discontinue permanently
- Confirmed or suspected pregnancy
Memory anchor
ARBs end in "-sartan" — no cough, less angioedema, but still hyperkalemia, hypotension, and pregnancy-contraindicated. "-sartan" replaces "-pril" when the cough drives a switch.
Practice Losartan questions
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