Alternating Current (AC) and Direct Current (DC) have slightly different effects on the human body, but both are dangerous above a certain voltage. The risk of injury changes according to the frequency of the AC, and it is common for DC to have an AC component (called ripple). Someone with special equipment can measure this, but the effect on a particular person is very difficult to predict as it depends upon a large number of factors. As a consequence you should always avoid contact with high voltage electrical conductors, regardless of the type of electrical current they are carrying.
More detailed technical information on electrical injury is given in the standard BS PD 6519 "Guide to the effects of current on human beings and livestock - Part 1: General aspects.'