South Central Ambulance Service (SCAS) was called to London Road – near Lidl – on the evening of October 19.
The patient was then taken to Queen Alexandra Hospital in Cosham.
A SCAS spokeswoman said: ‘SCAS were called at 6.22pm to reports of a medical emergency. We sent to the scene one ambulance crew who were assessing and treating one patient who was in a life threatening condition.
‘Following assessment and treatment at the scene the patient was taken to Queen Alexandra Hospital.’
Hampshire police said they were not called.