From the Research
Bactrim (sulfamethoxazole-trimethoprim) does not typically raise PTT (partial thromboplastin time) levels. PTT is a blood test that measures how long it takes for blood to clot, specifically evaluating the intrinsic and common coagulation pathways. While Bactrim can cause various side effects and has been associated with some blood disorders like thrombocytopenia (low platelets) or neutropenia (low white blood cells), it does not directly interfere with the coagulation cascade measured by PTT.
If a patient on Bactrim shows an elevated PTT, other causes should be investigated, such as liver disease, vitamin K deficiency, heparin therapy, or coagulation factor deficiencies. Patients taking Bactrim who experience unusual bleeding, bruising, or prolonged bleeding from cuts should contact their healthcare provider immediately, as these could indicate a blood disorder requiring medical attention, but this would not typically be due to PTT elevation specifically.
Some studies have reported cases of coagulopathy due to vitamin K deficiency caused by antimicrobial agents, including trimethoprim/sulfamethoxazole 1. However, this is not a direct effect of Bactrim on PTT levels. Other studies have reported cases of hyponatremia and hyperkalemia associated with trimethoprim/sulfamethoxazole therapy 2, but these electrolyte imbalances are not directly related to PTT elevation.
A recent study found that trimethoprim may affect the kinetics of creatinine, sodium, and potassium in the proximal and distal tubules in a dose-dependent manner without changing the glomerular filtration rate 3. However, this study did not investigate the effect of Bactrim on PTT levels.
In summary, Bactrim does not typically affect PTT levels, and any elevation in PTT should be investigated for other causes. Patients taking Bactrim should be monitored for signs of bleeding or blood disorders, but this is not typically related to PTT elevation.