Blackpool Victoria Hospital's accident and emergency department is tonight warning people not to attend unless absolutely necessary.
It issued a warning at around 5.30pm this evening to say the department was especially busy.
In a post on social media, the emergency department said: "The department is significantly overcrowded currently with a high number of patients being cared for.
"Please attend for emergencies only. If you attend then please be patient.
"Patients will be seen according to clinical need."
It is the fourth time in April the department has made this particular plea, asking patients to consider using their pharmacist, or the area's urgent treatment centres.