"We've forgotten what bread tastes like," 27-year-old Mohamed told AFP from the town near the Lebanese border.
People trapped in Madaya are starving to death, Mohamed and other residents said in interviews, and few have any hope.
"The situation has become very tragic," he said.
Some 40,000 people, mostly civilians, are believed to be in the town in Damascus province, many of them displaced from the neighbouring rebel stronghold of Zabadani.
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They are encircled by regime forces, and last year were part of a deal, along with two rebel-besieged villages in northwestern Syria, to allow aid in and the exit of civilians and the wounded.
But so far Madaya has seen only a one-off aid delivery three months ago, and residents, activists, and aid agencies describe dire conditions in the town now.
"There's nothing to eat anymore. Nothing but water has entered my mouth for two days," 32-year-old Momina said.
Mohamed said the cost of what food was available was astronomical.
"The situation has become very tragic. Very little can be smuggled in, so the prices of food are extremely high," he said.
"A bag of milk can go for USD 100, a kilo of rice for USD 150," he said.
According to the Britain-based Syrian Observatory for Human Rights, at least 10 people have died from lack of food and medicine in the town.
Another 13 have been killed by regime mines or snipers while trying to leave in search of food, the monitoring group said.
"Many of the town's residents have been forced to survive on weeds and others pay huge sums of money at government checkpoints to obtain food," Observatory director Rami Abdel Rahman said.
"One resident who was really suffering put his car on sale for the price of 10 kilos of rice. He is one of many who did that. He didn't manage to sell it, and a relative of his died as a result of the food shortages," he added.