An air ambulance landed at the Red Funnel terminal on Tuesday morning.
Paramedics rushed to the ferry terminal in Town Quay to attend a medical incident just before 11.15am.
Two doctors and a specialist paramedic treated a patient before returning to base.
The patient was not airlifted to hospital.
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A spokesperson from Hampshire and Isle of Wight Air Ambulance said: "The Air Ambulance was dispatched to a medical incident at 11:12 on 25/4/23.
"The Critical Care Team of two doctors and a specialist paramedic provided medical treatment to a patient before returning to base. We did not transfer the patient to hospital."
