Mastoiditis is an infection of the mastoid bone’s cell system, caused by bacteria. It can present in various forms such as acute, coalescent, chronic, and masked mastoiditis. It is the most frequent complication of acute otitis media, affecting up to 0.4% of cases, predominantly in young children. The primary pathogen causing acute mastoiditis is Streptococcus pneumoniae, followed by Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, Haemophilus influenzae, Escherichia coli, and Proteus mirabilis. Typical symptoms include fever, ear pain, post-auricular erythema, tenderness, protrusion of the pinna, acute otitis media, and sagging of the posterior-superior external auditory canal (EAC) wall visible on otoscopy or a subperiosteal abscess. Patients may also exhibit leukocytosis, a low-grade or septic fever, and occasionally chills. Computed tomography (CT) scanning is the most commonly used imaging technique, which can show loss of mastoid air cell trabeculations, local bone destruction, and the presence of soft tissue within the mastoid cavity and middle ear cleft. Complications can be intratemporal (such as facial nerve palsy and labyrinthitis), extracranial (such as subperiosteal abscess and Bezold’s abscess), or intracranial (such as meningitis and subdural/brain abscess). Treatment options for acute mastoiditis range from intravenous antibiotics alone or in combination with myringotomy or tympanostomy tube placement, to subperiosteal incision and drainage, or mastoidectomy.