Medical workers at the Hungarian border have warned of desperate conditions for pregnant women and the risk of disease spreading at the under-equipped camp where thousands of refugees are streaming in daily.
A huge outpouring of sympathy from across Europe has brought dozens of vehicles loaded with aid supplies from Britain, Austria, Germany and elsewhere to the filthy camp in the border town of Roszke.
But while blankets, clothes and food pile up around the muddy fields, doctors say they are worried about the lack of sanitation and medical supplies.
"When you have no running water, no way to clean and people are arriving with contagious diseases, you have a problem," said Teresa Sancristobal, head of the Doctors Without Borders site team.
A priority for the doctors on site is pregnant women, many of whom have walked for weeks on their journey from the warzones of the Middle East.
"We have a lot of pregnant women who are just exhausted and can't take it anymore," said Sarah Schober, 28, a medical student leading a volunteer team from Vienna.
"All we have to give them is magnesium and small doses of schnapps for the cramps, and there are very few field beds for them to rest."
Exhaustion and dehydration are common. One volunteer described finding a 12-year-old girl who had walked several kilometres with a broken knee after being hit by a taxi in Serbia.
An over-stretched UN refugee agency has organised for more toilets and clean-up operations, but faces big challenges as government buses are slow to move refugees on to registration centres, leaving thousands to sleep in the fields every night.