The border zone is a bustling area. A line of cars, taxis and minibuses wait to go through Syrian customs procedures, whilst dozens of volunteers and aid workers hand out food and drink to new arrivals.
Although the influx is less frantic than in the earlier days of the two-week-old Israeli bombardment, many poorer families from ravaged areas of Lebanon are still making their way across the border.
According to UN figures, more than 140,000 Lebanese, 1,000 Palestinians and 20,000 other foreign nationals have crossed into Syria since fighting began.
Reem Haida, an engineer who now volunteers for the Syrian public relations association, said: "My job is to act as a coordination point between the homeless Lebanese arriving at the border and the Syrian families in Damascus who have offered to house them.
"So far we’ve had almost 7,000 Syrian families sign up to house Lebanese people who have fled."
On the Syrian side of the border, the public and private sector have laid on free buses to Damascus for those without transport, whilst Syriatel, a wireless phone company, have provided free-to-use telephones.
On Monday, the UN office in Damascus launched a flash appeal for $13.6million in emergency aid to meet the essential needs of stranded families. The plea is part of a wider campaign launched this week by the UN to raise $160million and help tackle the unfolding humanitarian crisis.
Of those now stranded indefinitely in Syria, the UN has identified 20-25,000 people – mainly poor Lebanese families with few belongings - as being the most vulnerable.
Laurens Jolles, acting-representative at the UN high commission for refugees (UNHCR) office in Syria, said: "Local efforts have been relatively speedy and well-organised, particularly from the Syrian red crescent.
"But there will come a time when this will naturally begin to wane, as it would anywhere, and resources will run low. We have to make sure we are prepared for that and UNHCR is opening three new offices in Homs, Tartous and Aleppo."
Although the Syrian authorities have opened their gates to most people fleeing Lebanon, including US citizens who normally require a visa in advance, they have imposed tighter restrictions on Palestinian refugees normally resident in Lebanon.
The UN relief works agency (UNRWA) has made a formal request to the Syrian government to allow all Palestinians entry on humanitarian grounds, but those stranded at the border have been told by immigration officials that they must wait for more paperwork to arrive in Damascus.
In the meantime, dozens of Palestinian families are effectively stuck in a kind of no-man’s land between the two countries, having officially left Lebanese soil but unable to enter Syria. Many have been here for over a week, bewildered that the Syrians have allowed in virtually every other nationality.
One Palestinian woman said: "I have a Lebanese-Palestinian passport but they won’t let me in. I’ve been here 12 days already. They give us all the food and water we want, but all I want is to get into Syria and get some shelter."
There are 350,000-400,000 Palestinians in Lebanon, the majority of whom live in one of the refugee camps. Although many have joint Lebanese passports, their status and rights in Lebanon are highly restricted.