What are the risks of having an electrocardiogram?

None. An electrocardiogram is a noninvasive test that records the electrical activity of the heart from multiple directions. There is no risk associated with an electrocardiogram.
Are you confused ? They do not run electricity through your body to do an EKG. The process is the equivalent of detecting natural electrical impulses that move through your heart using passive sensors. Think of a compass pointing where a magnet pulls it.
Virtually zero. An electrocardiogram only requires the application of adhesive electrodes for about a minute to record the electrical activity of the heart. Rarely individuals may have allergies to the adhesive and develop a reaction. Aside form minor skin irritation, there are no real risks.

Related Questions

What are the risks of having an exercise electrocardiogram (ecg)?

Very safe. If exercise is going to make you seriously sick, it'll happen where they'll probably be able to resuscitate you -- disease discovered would have caught up with you soon enough without anyone on-scene to help. But mostly -- congratulations on considering a fitness screen -- my hope is that it'll inspire you to exercise to your maximum as often as you can. Read more...