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Case Reports
. 2025 Sep 8;17(9):e91830.
doi: 10.7759/cureus.91830. eCollection 2025 Sep.

Sudden-Onset Severe Thrombocytopenia Secondary to Trimethoprim-Sulfamethoxazole

Jonathan Spadafora  1 , Philip Spadafora  1 , James Spadafora  1 , Jonathan Starcke  1 , Philip F Spadafora  2
Affiliations
Case Reports

Sudden-Onset Severe Thrombocytopenia Secondary to Trimethoprim-Sulfamethoxazole

Jonathan Spadafora et al. Cureus. .

Abstract

Drug-induced immune thrombocytopenia (DITP) is a rare but life-threatening condition characterized by a sudden and serious drop in the number of platelets from drug-dependent antibodies against platelet glycoproteins. We report the case of a 57-year-old man who developed severe thrombocytopenia and mucocutaneous bleeding following a short course of trimethoprim-sulfamethoxazole (TMP-SMX) for presumed tick-borne disease. The patient experienced bleeding gums, pinpoint rashes, bruising, and extreme fatigue. The laboratory tests indicated a severely low platelet count of 1 × 1.0 × 10³/µL combined with a high immature platelet fraction (IPF). Workup for both infection and autoimmune disorders would be negative, along with the absence of intracranial hemorrhage demonstrated on imaging. The timeline and clinical picture suggested that TMP-SMX was the most likely culprit. The patient was placed on supportive care, including platelet transfusion and re-start of doxycycline after discontinuation of the drug. His platelet count began to rise, and his symptoms improved; he was discharged without issues. By presenting this instance, we place high importance on early recognition and immediate withdrawal of the offending agent to prevent life-threatening bleeding. Though confirmatory testing of antibodies is available, clinical diagnosis remains the gold standard due to delays in testing and availability.

Keywords: drug‑induced immune thrombocytopenia; petechiae; platelet transfusion; sudden-onset thrombocytopenia; tmp‑smx (trimethoprim‑sulfamethoxazole).

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Conflict of interest statement

Human subjects: Informed consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Figures

Figure 1
Figure 1. Ecchymotic lesion from tick bite on the patient’s right middle back
Figure 2
Figure 2. Pinpoint petechiae on the bilateral shoulder and chest
Figure 3
Figure 3. CT scan of the patient's brain
No acute intracranial abnormalities
See this image and copyright information in PMC

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