The Montreal Children's Hospital is overwhelmed with patients and asking that only emergency cases be referred to the site.

"[We are] currently experiencing a high volume of patients requiring hospitalization or critical care. This increase puts a strain on emergency services, who need to care for patients waiting for a bed," the hospital tweeted on Sunday afternoon.

"We are currently unable to see patients whose condition is non-urgent (categories 4 and 5). We ask these patients to consult their doctor, go to a rapid access clinic or call Info-Santé at 8-1-1," a second tweet read.

Santé Montreal describes category four as not requiring immediate care, like a "minor allergic reaction," for example. Category five means your health problem "isn’t serious," like gastroenteritis or a urinary infection, so a medical clinic or CLSC could offer treatment.

Meanwhile, categories one through three entail much more serious issues:

• Category 1: A life is in danger and requires immediate care (i.e., shock, coma).
• Category 2: A condition that requires rapid intervention (i.e., intense chest pain, difficulty breathing, signs of a heart attack).
• Category 3: A health problem that is serious but not life-threatening (i.e., fracture, signs of infection).