Non-steroidal anti-inflammatory drugs (NSAIDs) and paracetamol are the common analgesics used in children who experience mild to moderate pain. NSAIDs-related case of aseptic meningitis or meningism in healthy adolescent is relatively uncommon. We report a case of an 11-year-old boy with underlying bronchial asthma who had recent intake of three doses of diclofenac (50 mg), presented with signs and symptoms mimicking acute meningism. The boy initially presented to the emergency department after he experienced throbbing headache, dizziness, nausea and persistent vomiting for about 15 times per day for the past 2 days. He did not report presence of any auditory or visual hallucination; however, he claimed to have a bit of photophobia. Signs and symptoms occurred soon after the second dose of diclofenac. Besides, he was also taking oral antibiotic Augmentin for his left epididymo-orchitis problem and famotidine for prevention of gastritis prescribed by general practitioner. Vital signs were normal, and review of systems did not find any abnormality. Neurological assessment found no significant deficit, no cerebellar sign, negative Babinski test and no sign of meningism. Patient did not have frequent fall, head trauma or any family history of neurological diseases. A provisional diagnosis of meningoencephalitis was made after review by specialist. The parents of the boy did not give consent to conduct spinal tap. Upon further examination, urgent contrast-enhanced computed tomography was done and clinical neurological assessment was not suggestive of meningoencephalitis. Antibiotics treatment for meningoencephalitis was stopped 12 h after hospitalization. Although this case was not diagnosed as aseptic meningitis, timeline of diclofenac intake, onset of symptoms, clinical manifestations and quick resolution symptoms after drug discontinuation were supportive of a temporal relationship between diclofenac and meningism. Paracetamol was given to relieve the headache, vomiting resolved after one dose of intravenous metoclopramide plus ranitidine, and patient was well throughout the 5 days in ward. This adverse effect of NSAIDs is very rare and continuous effort in pharmacovigilance can help to raise awareness among clinicians.