Main Symptoms of Brain Abscess A brain abscess is a pocket of pus that forms deep inside the brain tissue. It starts as a small infection and grows into a swollen, pressurized bubble that can damage nearby brain cells and raise pressure inside the skull. Symptoms often begin quietly but worsen quickly as the abscess expands. The first sign is a persistent, pounding headache that gets worse over days. It may feel like pressure building from the inside and is often more intense in the morning or when bending forward. Fever is common, but not always high. Many people feel... Learn more