Angiotensin II receptor blockers (sartans)
ATC code: C09CA01 (Losartan)
Selective AT1 angiotensin II receptor antagonist – blocks vasoconstriction, aldosterone secretion, sympathetic activation, and vascular smooth muscle proliferation. Unlike ACE inhibitors, it does not cause dry cough (no bradykinin accumulation). The active metabolite EXP3174 (formed via CYP2C9 and CYP3A4) provides most of the pharmacodynamic effect. Used in hypertension, HFrEF with ACE-inhibitor intolerance, and diabetic nephropathy.
First line
Losartan slows progression of diabetic nephropathy in type 2 diabetes. The RENAAL trial showed a 25 % reduction in doubling of creatinine and a 28 % reduction in end-stage renal disease. Monitor creatinine and potassium 1–2 weeks after initiation.
Diabetic nephropathy in type 2 diabetes patients.
First line
ARBs are an alternative to ACE inhibitors in HFrEF when ACEi are not tolerated due to cough. Mortality and hospitalization reduction is comparable to ACEi based on CHARM-Alternative (candesartan) and ELITE II (losartan) trials. Titration to maximum tolerated dose is mandatory.
Prescribed when ACE inhibitors are not tolerated (most commonly due to cough).
First line
Losartan is a first-line antihypertensive. Start at 50 mg once daily, maximum 100 mg. Prescribed as an alternative to ACE inhibitors, especially when ACEi-induced cough develops. The LIFE trial showed losartan superior to atenolol for stroke risk reduction in patients with hypertension and LVH.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Losartan is an angiotensin II receptor blocker, the first ARB to be registered. It is prescribed for hypertension, heart failure, and diabetic nephropathy in type 2 diabetes ( 2023, KDIGO 2024, SEH-LELHA). In anti-aging regimens, losartan is positioned as an anti-aging drug acting on the renin-angiotensin system. In people with normal blood pressure, no clinical studies of prophylactic use exist, and a rejuvenating effect has not been demonstrated. The drug can cause dizziness, hyperkalemia, angioedema in predisposed people, and teratogenicity. If losartan was prescribed to a healthy person, consider seeking a second opinion.
16 pairs found. Sorted from critical to minor.
Mechanism
Dual RAAS blockade (ACE-I + ARB). Additive hyperkalaemia, hypotension, and acute kidney injury risk without added benefit.
Symptoms
Weakness, postural dizziness, syncope. Reduced urine output, rising creatinine. Weakness and paraesthesia from hyperkalaemia.
Management
The combination is not prescribed. Choose one: ACE-I if tolerated, ARB if there is a dry cough.
Sources
Mechanism
Similar to enalapril + celecoxib. NSAIDs reduce renal blood flow; the ARB (losartan) lowers glomerular pressure. The combination causes acute kidney injury.
Symptoms
Reduced urine output, rising creatinine and potassium, oedema. Symptoms appear earlier in older patients and in chronic kidney disease.
Management
For prolonged celecoxib therapy, check creatinine 2–4 weeks after start, then every 3 months. In older patients and chronic kidney disease, paracetamol is preferable.
Mechanism
Trimethoprim blocks sodium channels via an amiloride-like mechanism, additively with an ARB (losartan) causing hyperkalaemia. In older patients, sudden death risk rises.
Symptoms
Muscle weakness, paraesthesia, slowed pulse, arrhythmias. ECG: peaked T waves, widened QRS. Severe cases progress to cardiac arrest.
Management
During co-trimoxazole therapy, check potassium 3 days after start. In older patients and chronic kidney disease, prefer alternative antibiotics (nitrofurantoin, fosfomycin).
Mechanism
Dual RAAS blockade: ACE-I blocks angiotensin II formation, ARB blocks its receptors. Additive risk of hyperkalaemia, hypotension, and acute kidney injury without additional clinical benefit.
Symptoms
Weakness, dizziness on standing, syncope. Reduced urine output, rising serum creatinine. Weakness and paraesthesia from hyperkalaemia. Symptoms typically appear in the first 1–4 weeks.
Management
The combination is not prescribed. Large trials (ONTARGET, ALTITUDE) showed no benefit and more adverse effects. Choose one agent: ACE-I if tolerated, ARB if there is a dry cough or intolerance.
Sources
Mechanism
Losartan (ARB) reduces aldosterone synthesis and angiotensin-dependent constriction of glomerular afferent arterioles. In a volume-depleted patient on a loop diuretic, the first losartan dose can sharply lower glomerular blood flow and trigger acute kidney injury.
Symptoms
Sharp blood pressure drop on the first dose: dizziness, syncope. Reduced urine output, rising creatinine. Weakness and paraesthesia from hyperkalaemia.
Management
The combination is standard in hypertension and heart failure. Before starting losartan, confirm there is no dehydration (after intensive diuretic therapy). Take the first dose in the evening, lying down. Check potassium and creatinine at 1 week.
Sources
Mechanism
A thiazide diuretic plus an ARB synergistically lower blood pressure: the thiazide reduces circulating volume, losartan vasodilates by suppressing the RAAS. This is a target combination in hypertension and available as a fixed-dose product (losartan + hydrochlorothiazide).
Symptoms
Excessive blood pressure drop during titration: postural dizziness, syncope. Hypokalaemia and hyponatraemia from the thiazide, plus a mild rise in creatinine, can occur in the first weeks.
Management
The combination is a treatment standard. Doses are individualised, usually starting with losartan 50 mg + hydrochlorothiazide 12.5 mg/day. Check potassium, sodium, and creatinine 2–4 weeks after start, then annually.
Sources
Mechanism
NSAIDs reduce renal blood flow via prostaglandin blockade. The ARB (losartan) lowers glomerular pressure. The combination causes acute kidney injury, especially in older patients, chronic kidney disease, and dehydration.
Symptoms
Reduced urine output, rising creatinine and potassium, oedema. Symptoms appear earlier in older patients and in chronic kidney disease.
Management
Avoid prolonged combination. If ibuprofen is needed for a short course, use the minimum effective dose for 5–7 days with pantoprazole cover and creatinine monitoring. For chronic analgesia: paracetamol or celecoxib.
Mechanism
Losartan, like ACE inhibitors, reduces lithium renal clearance via angiotensin blockade of the efferent arteriole. Lithium rises 20–40%. Effect described for all ARBs.
Symptoms
Tremor, nausea, confusion within 1–3 weeks of losartan start.
Management
Check lithium on day 7, day 14 and at one month. Lithium may need a 25–50% reduction.
Sources
Mechanism
Losartan (angiotensin II receptor blocker, ARB) suppresses the renin-angiotensin-aldosterone system and reduces aldosterone release. Spironolactone directly blocks aldosterone receptors. Both retain potassium.
Symptoms
Muscle weakness, paraesthesia in the limbs, slowed pulse, arrhythmias. ECG shows peaked T waves and widened QRS. Severe cases progress to cardiac arrest. Symptoms typically appear within 1–2 weeks of starting the combination.
Management
The combination is appropriate in heart failure. Check potassium and creatinine 1 week after start, then monthly. If potassium exceeds 5.5 mmol/L, reduce the dose of one agent; above 6.0 mmol/L, stop one of them.
Mechanism
High aspirin doses (above 1 g/day) weaken the ARB's antihypertensive effect via vasodilator prostaglandin suppression. At cardioprotective doses, the effect is clinically minor.
Symptoms
Gradual blood pressure rise at high aspirin doses. At cardioprotective doses, no significant changes.
Management
Cardioprotective aspirin doses (75–100 mg) are acceptable without adjustment. At high doses, monitor blood pressure and increase losartan if needed. Alternative analgesic: paracetamol.
Sources
Mechanism
Additive hypotension. Alprazolam sedation may mask orthostatic symptoms.
Symptoms
Lower blood pressure, postural dizziness, fatigue. Older patients: fall risk.
Management
In older patients, check standing and sitting blood pressure 1–2 weeks after start. Alternative anxiolytic: hydroxyzine or a short lorazepam course.
Mechanism
Additive orthostatic hypotension. Losartan (ARB) dilates vessels; amitriptyline blocks α1-adrenoceptors. Older patients: fall risk.
Symptoms
Postural dizziness, syncope, fatigue. Older patients: fall and fracture risk.
Management
In older patients, check standing and sitting blood pressure 1–2 weeks after starting amitriptyline. For neuropathic pain, alternative: gabapentin or pregabalin.
Mechanism
Synergistic blood pressure reduction – a target hypertension combination. Amlodipine dilates peripheral vessels; losartan (ARB) blocks the renin-angiotensin system.
Symptoms
Older patients may have symptomatic and orthostatic hypotension, dizziness on standing. With the first losartan dose: risk of marked blood pressure drop.
Management
Standard hypertension treatment (fixed-dose product available). Take the first losartan dose in the evening, lying down. Check blood pressure and creatinine 1–2 weeks after start.
Sources
Mechanism
ARBs, like ACE inhibitors, improve tissue insulin sensitivity. In patients on insulin or sulfonylureas with metformin, the glucose-lowering effect may be amplified.
Symptoms
Signs of hypoglycaemia: sweating, tremor, hunger, tachycardia, confusion. Symptoms appear at glucose below 3.9 mmol/L.
Management
On metformin alone, no dose adjustment needed. On insulin or sulfonylureas, intensify glucose self-monitoring for the first 2 weeks after starting losartan. The effect is helpful in type 2 diabetes with arterial hypertension.
Sources
Mechanism
Target combination in heart failure and arterial hypertension. Synergistic blood pressure reduction. The ARB does not mask the adrenergic response to hypoglycaemia.
Symptoms
On starting, in older patients: symptomatic hypotension, dizziness. Metoprolol bradycardia is amplified as sympathetic activation drops.
Management
Start both at minimal doses with up-titration every 2 weeks to target. Check standing/sitting BP, heart rate, creatinine and potassium at 2 weeks. In diabetes, monitor for hypoglycaemia: metoprolol is cardioselective and weakly masks adrenergic symptoms.
Sources
Mechanism
Prednisolone retains sodium and water via mineralocorticoid effect, blunting the ARB's antihypertensive effect. Both also contribute to hyperkalaemia in CKD.
Symptoms
Return or rise of blood pressure, leg oedema. Weakness, fatigue, paraesthesias, arrhythmia. Symptoms develop at potassium above 5.5 mmol/L; life-threatening above 6.5 mmol/L.
Management
For short prednisolone courses (3–7 days), no specific adjustment needed. For long-term therapy, check BP weekly in the first month. If BP rises, increase losartan or add a thiazide. Potassium and creatinine every 2 weeks.
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FDA category D. Drugs acting on the renin-angiotensin system cause fetal renal injury, oligohydramnios, pulmonary and skeletal hypoplasia. Discontinue when pregnancy is planned.
No data on excretion in breast milk. Not recommended during breastfeeding. Alternative antihypertensives are chosen if therapy is needed.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Losartan is evaluated for the following indications with varying evidence strength: Chronic kidney disease (evidence tier A), Hypertension (evidence tier A), Heart failure (evidence tier A). See the full indication matrix with dosing and citations above on this page.
Common side effects of Losartan (≥ 1 in 100): Dizziness, Hyperkalemia, Hypotension (more common with hypovolemia), Creatinine elevation. See the Safety section for uncommon and serious reactions.
FDA category D. FDA category D. Drugs acting on the renin-angiotensin system cause fetal renal injury, oligohydramnios, pulmonary and skeletal hypoplasia. Discontinue when pregnancy is planned.
No data on excretion in breast milk. Not recommended during breastfeeding. Alternative antihypertensives are chosen if therapy is needed.
Losartan is contraindicated in: Pregnancy (all trimesters); Severe hyperkalemia; Bilateral renal artery stenosis or stenosis of a single functioning kidney; Concurrent aliskiren in patients with diabetes or CKD. Full list in the Safety section.