Ryanair said the jar held "a vegetable oil/mushroom soup type substance"
A Ryanair plane was forced to land in Germany after a passenger had an allergic reaction to mushroom soup.
The soup leaked onto the man from a jar in an overhead locker on a flight from Budapest to Dublin on Monday, the airline said.
His neck reportedly swelled up and he struggled to breathe, forcing the plane to divert for emergency medical help.
On the same day, another Ryanair flight had to make an unscheduled landing in France after losing cabin pressure.
A spokeswoman for Ryanair said the jar contained "a vegetable oil/mushroom soup type substance".
"It is procedure when a passenger requires medical attention to divert to the nearest airport," she said.
"The cabin crew and pilot take that decision."
The Boeing 737 landed at Frankfurt Hahn Airport where the man was treated by doctors.
The plane was delayed for two hours before continuing its journey to Dublin.
The episode was one of a series of high-altitude incidents in recent days.
On Monday, oxygen masks were deployed on a Ryanair flight from Bristol to Barcelona Girona when the cabin depressurised.
The plane was forced to land at Limoges Airport in central France and 16 people were taken to hospital suffering from ear pain.
Then on Tuesday, a Thomsonfly plane to Gatwick had to turn back to Croatia just seven minutes after take-off when a fire broke out in an oven.
A spokesman said the fire was "immediately contained" and there was "no danger to passengers or crew".
Passengers were delayed for eight hours while a replacement plane was flown from Manchester.