New-Onset Manic-Spectrum Symptoms Temporally Associated With Co-amoxiclav Exposure: A Case Report.

Antibiotics have been associated with a range of neuropsychiatric adverse effects, including manic-spectrum symptoms. However, such side effects are uncommon, and the mechanisms underlying these presentations remain uncertain.  A 62-year-old female with no previous psychiatric history developed manic-spectrum symptoms shortly after receiving co-amoxiclav for a suspected dental infection. Approximately two days after initiation of treatment, she developed marked anxiety, reduced sleep, irritability, restlessness, racing thoughts, increased speech, an elevated mood, and paranoid ideas. Symptoms persisted for approximately eight days after discharge from the general hospital, then gradually improved and subsequently resolved. Although the presentation included multiple symptoms commonly associated with mania, formal diagnostic criteria for mania or hypomania could not be confidently established retrospectively. Therefore, the presentation is described as manic-spectrum symptoms. Investigations, including neurological examination, magnetic resonance imaging of the brain, thyroid function tests, metabolic investigations, and immunological and viral screening, did not identify an alternative neurological, endocrine, metabolic, or infective explanation for the presentation. During the acute phase, she was commenced on olanzapine and received a short course of benzodiazepines. There was no documented recurrence during follow-up. This case describes new-onset manic-spectrum symptoms occurring in temporal association with co-amoxiclav exposure. Although the close temporal relationship between antibiotic exposure, symptom onset, and subsequent resolution raises the possibility of a medication-associated adverse reaction, alternative explanations, including familial bipolar vulnerability and concomitant psychotropic treatment, prevent firm causal attribution. Clinicians should consider recent medication exposure as part of the assessment of new-onset psychiatric symptoms, particularly in patients without a previous psychiatric history.