Although rare, transient psychosis related to trimethoprim-sulfamethoxazole (TMP-SMX) intake has been described previously. Most of these descriptions have involved the immunocompromised and/or the elderly. From literature review, it doesn’t appear there has ever been a case describing TMP-SMX-associated psychosis in a patient with Down syndrome. A case of such is described below.

A 46-year-old female with a past medical history consisting of Down syndrome presented to the emergency department after experiencing distressing visual hallucinations for two days. The patient had no past history of hallucinations. Of note, the patient was recently diagnosed with a skin ulcer and was prescribed TMP-SMX for management. On examination, the patient was restless. She continuously looked around various parts of the room, describing ongoing hallucinations. The rest of her physical exam was unremarkable, except for the healing ulcer involving her left buttock. On admission, her vital signs, laboratory analysis, and imaging were unremarkable. The patient’s TMP-SMX was discontinued on admission, and the patient was observed for four days. By the end of her hospital stay, she was no longer exhibiting any evidence of ongoing psychosis. She was discharged with education to avoid future use of TMP-SMX.

Although TMP-SMX-related psychosis is rare, it is important to be aware of when considering TMP-SMX is a commonly prescribed antibiotic. Considering that TMP-SMX-associated psychosis in the immunocompromised has been described previously, it is reasonable to assume that patients with Down syndrome would be at increased risk of developing psychosis given their inherent immunocompromised state. Unfortunately, Down syndrome patients may be subject to more bias than that of other clinical groups, with practitioners incorrectly assuming their psychosis is related to a more organic etiology rather than an iatrogenic one. It may be reasonable to consider other antimicrobial agents in patients with Down syndrome. Given the relatively small patient population, it will be difficult in the future to determine just how common this medication-related psychosis occurs in this population. If more of these cases develop, it could prove beneficial to share them in hopes of preventing future transient psychosis in this potentially vulnerable group of patients.

References and Resources

1. Dieudonné, Y. (2020). Immune Defect in Adults With Down Syndrome: Insights Into a Complex Issue. Frontiers in Immunology.
2. Dykens, E. (2015). Psychiatric disorders in adolescents and young adults with Down syndrome and other intellectual disabilities. Journal of Neurodevelopmental Disorders.
3. Sunil, P. (2016). Trimethoprim-Sulfamethoxazole–Induced Psychosis Culminating in Catastrophic Self-Injury: A Case Report. The Primary Care Companion For CNS Disorders.