Any passengers subject to immigration control detained by the immigration service would normally be kept in holding rooms at ports only for short periods.
There is no on-site health care provision in those holding rooms without sleeping accommodation. In the event of a medical emergency, an ambulance is called. Where medical advice is required (for example relating to medication) arrangements are in place for detention custody officers to phone an advice line similar to NHS Direct, who advise on what further medical attention is required. Detainees held in immigration removal centres have access to on-site health care.