Heart failure with reduced ejection fraction is a syndrome consisting of symptoms (dyspnoea, fatigue, swelling) and/or signs of congestion (pulmonary crackles, oedema). It is caused by structural and/or functional pathologies, most commonly ischaemic heart disease, entailing elevated cardiac filling pressures and can result in low cardiac output. Medical treatment has evolved during the recent decades as outlined in this review, and a 4-pillar treatment strategy is recommended including a renin-angiotensin-aldosterone system blocker or sacubitril/valsartan, a betablocker, a mineralocorticoid antagonist, and an SGLT2 inhibitor.