New Delhi, Oct. 12 -- Antihistamines, diuretics, eye drops and antibiotics are among the drugs she distributes. She charges nothing.

Projects like Mendoza's, called "Medicine Is Not for Sale," have become a lifeline for Cubans struggling to find increasingly scarce medications as the country's economic crisis deepens, compounded by U.S. energy and financial restrictions imposed since January.

Online sellers, street vendors and WhatsApp and Telegram groups have also stepped in to fill gaps left by state pharmacies, which for decades were the main source of subsidized medicines.

The shortages have become so severe that Cuban authorities issued regulations in July allowing private pharmacies to operate - a historic change to the country's...