Ahmed Kamal, an aide to the minister responsible for the subsidies, blamed the private sector, a scarcity of Egyptian hard currency and rising global prices for the sugar shortage. He said that private importers were expected to bring in some of the 800,000 tons of sugar that Egypt must purchase from abroad annually, about a quarter of the nation’s yearly demand for 3.2 million tons, but that the country had fallen short of its goal this year.

Mr. Kamal said the problem had been exacerbated by business owners hoarding supplies and by the news media whipping up angst. He added that the government still had a four-month supply of sugar.

But little of it was available in Bulaq, the Cairo neighborhood where Mr. Gebaly’s shop was the only subsidized grocery reliably open — and he mostly turned people away.

“All I say, all day, is: ‘There’s no sugar, there’s no sugar, there’s no sugar, tomorrow, tomorrow, tomorrow,’ ” Mr. Gebaly said, before he was interrupted by a call of another customer asking for sugar. An older man waiting nearby gave up, grumbling: “You keep saying, tomorrow! Tomorrow!”

Residents said that the other six shops in the neighborhood that were licensed to sell subsidized goods had closed to avoid a police crackdown, but that they sometimes opened after hours to sell sugar illegally to small-time confectioners, cafes and people. The subsidy police have already arrested two neighborhood sugar traders, residents said.

Sumaya Oweis, 37, said she had stopped making her beloved sweet rice pudding and had cut down on tea. On a recent morning, she smacked her 4-year-old son after he stuck his hand in the sugar bowl. But what was she to do about her husband?