Potassium (K+) is the most abundant cation in humans and is essential for normal cellular function. Alterations in K+ regulation can lead to neuromuscular, gastrointestinal, and cardiac abnormalities. Dyskalemia (i.e., hypokalemia and hyperkalemia) in heart failure is common because of heart failure itself, related comorbidities, and medications. Dyskalemia has important prognostic implications. Hypokalemia is associated with excess morbidity and mortality in heart failure. The lower the K+ levels, the higher the risk, starting at K+ levels below approximately 4.0 mmol/l, with a steep risk increment with K+ levels <3.5 mmol/l. Hyperkalemia (>5.5 mmol/l) has also been associated with increased risk of adverse events; however, this association is prone to reverse-causation bias as stopping renin angiotensin aldosterone system inhibitor therapy in the advent of hyperkalemia likely contributes the observed risk. In this state-of-the-art review, practical and easy-to-implement strategies to deal with both hypokalemia and hyperkalemia are provided as well as guidance for the use of potassium-binders. Display omitted •Potassium alterations may have life-threatening consequences.•Hypokalemia is associated with adverse outcomes likely via causal mechanisms.•Hyperkalemia leads to the stopping of renin angiotensin aldosterone system inhibitor that may have adverse consequences.•Correction of both hypokalemia and hyperkalemia offsets their associated risk.