"We are using those 'poopootov' bombs as we call them because they repress us with Molotov cocktails, with pellet guns and everything, and this is our only way to throw something at them," one protester told AFP, displaying a jar of brown liquid.
"The government is arbitrarily attacking us, whereas we are seeking a way to protest that we need a change of government -- and that is not the same thing."
Clashes between protesters and riot cops have left 38 people dead and hundreds injured since unrest erupted on April 1, according to authorities.
The casualties include a 27-year-old who died in the Wednesday protests in Caracas, as well as a 38-year-old who died two days after being shot in the head in a protest in the western city of Merida, the state prosecution service said.
A group of young protesters took excrement bombs from their backpacks as a crowd of some 3,000 protesters set off from a square in eastern Caracas heading for the Supreme Court in the center.
Demonstrators blame socialist President Nicolas Maduro for an economic crisis in the oil-rich state that has caused shortages of food and of basic supplies -- such as toilet paper.
