Between the dire shortages and hyperinflation plaguing crisis-ridden Venezuela, many people there have few good choices, left to rely on whatever they can find for sale by vendors on the Simon Bolivar bridge that links their country to Colombia.
Some of the drugs on offer are spoiled, adulterated, outdated, fakes or even placebos.
"I was dying in Venezuela for the lack of proper food or medication, of anti-retrovirals" to combat HIV, Plaza told AFP. He has been fighting the virus for five years.
His condition worsened in December when he contracted malaria. That was when he left Venezuela.
A storekeeper on Margarita Island, once a sunny Caribbean tourist mecca, he left behind his family, including his six-year-old son.
In the Colombian border town of Cucuta, an American charitable organization, which has helped thousands of migrants fleeing the Venezuelan crisis, was able to help him procure a free supply of anti-retrovirals.
"Thank God I'm here, on my feet," the 24-year-old smiled, wearing a baseball cap and a faded T-shirt. He survives by begging, but considers himself fortunate compared to those who have no choice but to rely on street "pharmacies."
For them, he feels "a lot of sadness, and rage."
The shortage of medicines in Venezuela is severe and getting worse. Thousands of patients suffering from chronic illnesses struggle to obtain treatment, according to NGOs and humanitarian groups that have been sharply critical of the government of President Nicolas Maduro, which has refused to acknowledge the gravity of the situation.
On the international bridge, crossed by some 35,000 people a day, a woman in a red beret sells 30 tablets of acetaminophen or paracetamol for 60 US cents.
At a nearby stall, Jose Alvarez offers pain remedies and sexual stimulants. That "is what sells best," he said, insisting that his supplies come from wholesalers. The former graphic designer, self-defense instructor and guard arrived in Cucuta two months ago.
Most of the vendors are from Venezuela. "There are a lot of people in need who have suffered for want of medicines," said Alvarez, a native of Valencia, west of Caracas.
One client, Maria Acevedo, a mother of three, regularly covers the 70 kilometers (40 miles) between Tachira in Venezuela, where she lives, and Cucuta, to find some of the many products that have disappeared from the shelves back home.
"Over there," said the 26-year-old housewife, "you find nothing in the pharmacies -- or else at exorbitant prices."
Worse than the disease
But the "cure" can sometimes be worse than the disease. Counterfeit or adulterated drugs can provoke cardiac problems, lesions of the liver or kidneys, pulmonary embolisms -- even death -- according to Colombia's National Food and Drug Surveillance Institute.
"There are mafias dedicated to (selling) fake drugs," former Colombian health minister Alejandro Gaviria (2012-18), told AFP. "There is no quality control."
The fiscal and customs police have broken up gangs devoted to such traffic, one police source in Cucuta said, speaking on grounds of anonymity.
Gaviria said AIDS and cancer patients do not get the complete array of medications they need from street vendors, meaning "they will have no effect."
In the face of the shortages, many Venezuelans are counting on the tons of humanitarian aid that arrived Thursday from the United States at the request of opposition leader Juan Guaido, who at this point has been recognized as the country's interim leader by more than 40 countries.
But President Nicolas Maduro warned that he would prevent the supplies stacking up in Cucuta from entering the country -- seeing them as a first step toward an American military intervention.
For Giovanni Plaza, standing on the bridge holding a certificate attesting to his HIV status, Maduro's stance is infuriating.
"Let them send this humanitarian aid, which every Venezuelan needs!" he said.