Voltage, current and your body
Here is the question everyone who thinks about electrical safety eventually runs into, and Ohm's law settles it.
The question
In an electrical accident, what brings about death — the potential difference, or the current? There is evidence that the current is what kills. But if voltage is not dangerous, what is the purpose of the warning signs about dangerous high-voltage cables?
Put the two together
Applying Ohm's law to voltage, current and resistance gives the equation that answers it. The current that travels through the body in an electrical accident is the potential difference between two points on the body, divided by the resistance between those two points.
I = V ÷ R
The current through the body depends on both the voltage across it and its own resistance.
So both matter, for different reasons
The question was a false choice. The current is what does the damage, and the voltage is what produces the current — so a warning about high voltage is a warning about the large current it is capable of driving.
Voltage drives it
A high voltage is a strong electric potential capable of producing a large current. A voltage is needed for charges to travel through a person at all.
Resistance limits it
The greater the resistance the body offers, the smaller the current that flows for a given voltage.
Your resistance is not a fixed number
The resistance the body offers is not always constant. It varies from person to person and with time, and it depends on the contact between the charges and the skin. The part of the body offering the greatest resistance is the skin. Sweat, being rich in salts and minerals, acts as a good electrical conductor, and the chemicals and fluids in blood are good conductors too.
Wet or broken skin is far more dangerous
The harm caused when a hand wet with sweat, or an area of broken skin, meets an electric wire is very much greater than the harm caused when clean, dry skin touches it. The voltage has not changed — your resistance has, and I = V ÷ R says the rest.