The East Anglian Air Ambulance (EAAA) was called to Framlingham after a man suffered a medical emergency.
The air ambulance arrived at the scene at about 10.40pm in the north Suffolk town on Tuesday.
He was treated and discharged at the scene and said to be in a stable condition.
A spokesperson for the EAAA said: “Anglia Two attended an incident in Framlingham at 10.40pm this evening.
“Dr Daniel Kornhall and critical-care paramedic Neil Flowers treat a male patient in his late twenties for a medical emergency. The patient was treated and discharged from the scene and they were in a stable condition.”