When warning signs do appear - things like headaches, nosebleeds and blurry vision - it's likely that your condition has already progressed to the point where it could be life-threatening.

People who get the headaches with aura - flashing lights, zig-zag lines, blurry vision or blind spots - are almost a third more prone to atrial fibrillation, they say.

Blurry vision and loss of vision can occur.

Other oculotoxic effects of digoxin include generalized blurry vision, as well as seeing a halo around each point of light.

It can also cause a variety of physical symptoms, including chest pain, blurry vision, nausea, and pins and needles.