What can cause fluid buildup in the forehead?

Fluid buildup in the forehead can be caused by several factors, including sinusitis, which leads to inflammation and fluid retention in the sinus cavities. Allergies can also trigger swelling and fluid accumulation in the nasal passages, affecting the forehead area. Additionally, trauma or injury to the forehead can result in localized swelling. Conditions affecting lymphatic drainage or systemic issues, such as kidney problems, may also contribute to fluid buildup.