Symptoms of infection after squeezing a pimple in the triangle include localized redness, swelling, heat, pain, eyelid edema, conjunctival bruising, limited anterior adduction of the eyeball, ptosis, and even systemic reaction with symptoms of intracranial infection, such as chills, fever, headache, and vomiting, which will require aggressive antibiotic treatment. The reason why the danger triangle of the face is susceptible to infection is because of the abundant blood supply in this area and the lack of valves in the venous blood vessels, known as venous valves, that prevent the backflow of blood. Because venous valves function as one-way valves to safeguard the flow of blood in the direction of the heart, once the veins do not have valves there can be venous reflux which can lead to infection and retrograde into the skull.