Increased peak plasma & trough conc of digoxin. May lead to significant increase in serum K w/ K-sparing diuretics eg, spironolactone, eplerenone, triamterene, or amiloride, K supplements, or K-containing salt substitutes. Reversible increases in serum conc & toxicity of lithium. Antihypertensive effect may be reduced w/ NSAIDs (ie, aspirin at anti-inflammatory dosage regimens, COX-2 inhibitors & non-selective NSAIDs). Prior treatment w/ high dose diuretics eg, furosemide (loop diuretic) & hydrochlorothiazide (thiazide diuretic) may result in vol depletion, & in risk of hypotension when initiating therapy w/ telmisartan. Increased BP-lowering effect w/ other antihypertensive medicinal products. Higher frequency of adverse events eg, hypotension, hyperkalemia & decreased renal function (including acute renal failure) w/ combined use of ACE inhibitors, ARBs or aliskiren. Hypotensive effects may be potentiated w/ baclofen, amifostine. Orthostatic hypotension may be aggravated by alcohol, barbiturates, narcotics, or antidepressants. Reduction of antihypertensive effect w/ corticosteroids (systemic route).