The excrement-filled containers are a way for the anti-government resistance to highlight the discrepancy in the force used by the police and the protesters. At least 36 people have been killed in civil unrest over the last six weeks.
Venezuela's opposition protests on Wednesday may be the messiest in a six-week wave of unrest as demonstrators prepare to throw faeces at security forces, adding to the customary rocks, petrol bombs and tear gas.
The new tactic has been dubbed the "Poopootov" in a play on the Molotov cocktails often seen at streets protests in Venezuela.
"They have gas; we have excrement," reads an image floating around social media to advertise Wednesday's "Shit March."
With deadly protests, inflation in the high triple-digits, shortages of the most basic medicines, and millions suffering food scarcity, the country is undergoing a major crisis.
For weeks, hundreds of thousands of people have taken to the streets, angry at the government of unpopular President Nicolas Maduro.
Security forces clashed with opposition protesters in the western Venezuela state of Tachira on Tuesday.
Masked protesters built barricades in the state capital of San Cristobal and threw rocks at police and members of the national guards, who fired tear gas to clear the streets.
Some opposition sympathisers are appalled at the plans to use faeces, both animal and human, calling it an unsanitary and inappropriate tactic even in the face of a government they despise.
Many note that throwing faeces could increase cases of infectious diseases which are soaring due to the lack of medicine as well as basic cleaning materials such as soaps and disinfectant.
A leading pharmaceutical association has said roughly 85 percent of medicines are running short. Venezuelans often barter medicine, post pleas on social media, travel to neighbouring countries if they can afford it, or line up for hours at pharmacies.
The Health Ministry stopped releasing figures after July 2015, amid a wider data blackout. However, local media reported on Tuesday figures from what seemed to be data recently published by the ministry. The data showed infant mortality rose 30 percent last year, maternal mortality shot up 65 percent and cases of malaria jumped 76 percent.
The statistics also showed a jump in illnesses such as diphtheria and Zika.
"Poopootov" not Molotov
"The kids go out with just stones. That's their weapon. Now they have another weapon: excrement," said a 51-year-old dentist preparing containers of faeces in her home for protesters to launch at authorities.
Messages have been going viral on Venezuelan WhatsApp groups giving step-by-step instructions and advice on putting together the #puputov cocktails.
While the opposition coalition has remained quiet on the strategy, some lawmakers have given it tacit acceptance.
"They use their weapons against us, so people are using what they have," said lawmaker Rafael Guzman, who on Monday was seen in the thick of tear gas throwing a canister back at security forces.
Military prosecuting citizens
Venezuela's opposition and rights campaigners voiced alarm Tuesday over claims that the military is holding and prosecuting scores of people detained in recent anti-government protests.
One lawyer working for those detained, Tony Marval, said 70 of them were being held in the northern state of Carabobo on the order of military courts.
The non-governmental criminal justice body Foro Penal said a further 11 were in a similar plight in Caracas and the north-western state of Lara.
Opposition lawmakers passed a motion Tuesday condemning the detentions.
"The constitution is clear: military courts are not for civilians. Bringing demonstrators before them is a violation of their human rights," said the opposition speaker of the legislature, Julio Borges.
The National Assembly resolution condemned the military detentions and charging of civilian protestors, calling it a human rights violation.
A senior military commander, Jesus Suarez, said that 780 people had been arrested in protests.
He said 251 of them were sent to military courts for charges such as attacking security forces and "rebellion."
Constitutional law expert Jose Vicente Haro said the detentions violate article 261 of the Venezuelan constitution which says military courts can only handle "crimes of a military nature."
"This is a violation of citizens' right to be judged by their peers in a civil manner with due process," Marval said.
Alfredo Romero, an attorney with Foro Penal, said that many of the detainees were arrested for robbery but face charges such as rebellion and contempt.
Venezuela's chief prosecutor Luisa Ortega has broken ranks with the government to speak out against detentions of protestors.
Maduro has the public backing of the military high command – a decisive factor in the political crisis, analysts say.
Clashes between protesters and riot cops have left at least 36 people dead and hundreds injured since the unrest erupted on April 1, according to authorities.
Demonstrators blame Maduro for an economic crisis that has caused food shortages in the oil-rich state.
His move to reform the constitution has further inflamed protesters, who say it is a ploy to resist calls for early elections.
Maduro says the crisis is a US-backed capitalist conspiracy against his elected socialist government. He has branded protesters "terrorists" and insurgents.