Anonymous mobile telephone text messages and even printed fliers this week have warned citizens to flee the city before all hell breaks loose.
"I got a BlackBerry message yesterday saying that the situation was bad and that we should leave Beirut," said one marketing student at the Lebanese American University.
"A lot of my friends got the same message."
Television channels have been feeding the psychosis, flashing any minor incident or loud sound as latest news.
Even the scheduled departure from Lebanon of a Western ambassador this week also sparked rumors she had packed her bags and fled.
"Our nerves are frayed," said a resident of Achrafieh, a Christian quarter in eastern Beirut.
"Everyone is jumpy and any rumor sends us into frenzy."
One woman, whose family is loyal to the Syrian Social Nationalist Party, an ally of Lebanon's powerful Hezbollah, said she had been called home this week after a relative received a tip-off.
"My brother called me yesterday in complete hysterics," said the 25-year-old, who requested anonymity.
"He said he had gotten news that something was going to happen that afternoon, and I left my office in Hamra (in western Beirut) and went home," she told AFP.
