Usually, hyperkalemia is associated with usage of digoxin. This is due to the blocking action of digoxin on the Na/K ase which results in accumulation of extracellular K+.

Most of the times, patients presenting with heart problems are already on diuretics before they are prescribed with digoxin. Diuretics cause hypokalemia as they result in excessive excretion of K+ from the body. Hypokalemia in turn causes digoxin toxicity. Digoxin toxicity does not cause hypokalemia, but hypokalemia can worsen digoxin toxicity.