What type of pediatric headache is characterized by unilateral pain, nausea, and vomiting?

The type of pediatric headache characterized by unilateral pain, nausea, and vomiting is a migraine. Migraines in children often present with a throbbing or pulsating quality, typically occurring on one side of the head. The accompanying symptoms of nausea and vomiting are significant hallmarks of migraines and are part of the diagnostic criteria used in both pediatric and adult populations.

Migraines can also be associated with other symptoms such as visual disturbances (aura), sensitivity to light and sound, and fatigue. These features together distinguish migraines from other types of headaches.

Tension headaches usually present as a bilateral tightness or pressure with less severity of pain, and they typically do not cause nausea or vomiting. Cluster headaches are characterized by severe unilateral pain but usually present with autonomic symptoms such as nasal congestion or tearing rather than nausea. Sinus headaches might be associated with sinus infections and are characterized by pressure and discomfort in the sinus areas, not the unilateral presentation or the specific nausea and vomiting seen in migraines.

Thus, when considering the specific symptoms outlined in the question, migraines are the clear answer due to their unique association with unilateral pain and nausea/vomiting.