Increased serum lithium conc & toxicity. Increased antihypertensive effect w/ baclofen, TCAs, neuroleptics, other antihypertensive agents. Attenuation of antihypertensive effect w/ NSAIDs including aspirin ≥3 g/day. Reduced antihypertensive effects w/ corticosteroids, tetracosactide. Perindopril: Higher frequency of adverse events w/ other ACE inhibitors, angiotensin II receptor blockers or aliskiren. Increased occurrence of hyperkalaemia w/ K salts, K-sparing diuretics, other ACE inhibitors, angiotensin II receptor antagonists, NSAIDs, heparin, immunosuppressants; co-trimoxazole. Risk of hyperkalaemia, worsening of renal function & CV morbidity & mortality increase w/ aliskiren in diabetic or impaired renal patients. Increased risk of angioedema w/ sacubitril/valsartan; estramustine; racecadotril; mTOR inhibitors (eg, sirolimus, everolimus, temsirolimus); gliptins (eg, linagliptin, saxagliptin, sitagliptin, vildagliptin). Increased blood-glucose lowering effect of antidiabetic medicines. Increased hypotensive effect w/ non-K-sparing diuretics; nitroglycerin & other nitrates or other vasodilators. Increased risk for leucopenia w/ allopurinol, cystostatic or immunosuppressive agents, systemic corticosteroids or procainamide. Enhanced hypotensive effects of certain anaesthetic drugs. Reduced antihypertensive effect w/ sympathomimetics. Nitritoid reactions w/ inj gold. Indapamide: Exercise caution when administered w/ Torsades de pointes-inducing drugs. Increased risk of hypokalaemia w/ K-lowering drugs (eg, amphotericin B (IV), glucocorticoids & mineralocorticoids (systemic route), tetracosactide, stimulant laxatives). Risk of toxic effects of cardiac glycoside. Increased incidence of hypersensitivity reactions to allopurinol. Caution w/ concomitant use of K-sparing diuretics. Lactic acidosis due to metformin caused by possible functional renal insufficiency linked to diuretics. Increased risk of acute renal insufficiency w/ iodinated contrast media (in cases of dehydration caused by diuretics). Risk of increased levels of Ca. Risk of increased creatinine levels w/ ciclosporin, tacrolimus.