The swelling of the mucus membranes lining the sinuses can lead to a condition commonly referred to as a “sinus headache.” Patients typically experience pain under, between, or above the eyes, and in the upper teeth. This discomfort is a result of inflamed mucus membranes blocking normal sinus drainage passages and causing mucus to become trapped in the obstructed sinuses. Sinus headaches and facial pain are often a symptom of sinusitis.