Kotrimoxazol

Co-trimoxazole (sulfamethoxazole/trimethoprim) combines two antibacterial agents that sequentially inhibit folate synthesis in bacteria. This combination provides broad-spectrum activity and is used for Pneumocystis jirovecii pneumonia (PCP) prophylaxis and treatment in immunocompromised patients, urinary tract infections, and certain other infections. Its use for common infections has declined due to side-effect concerns, but it remains essential for PCP.

How to Take Co-trimoxazole

Take co-trimoxazole with plenty of water, with or without food. Maintaining a good fluid intake throughout treatment is important to prevent crystalluria (crystal deposits in the urine). Complete the full prescribed course even if symptoms improve early.

Dosage and duration vary depending on the infection being treated. For urinary tract infections, courses are typically 5 to 7 days. For Pneumocystis pneumonia (PCP) prophylaxis in immunocompromised patients, a lower dose is taken on alternating days or three times weekly on a long-term basis.

UTI: 960 mg (one double-strength tablet) twice daily for 3 to 14 days. PCP treatment: 120 mg/kg/day in divided doses. PCP prophylaxis: 960 mg daily or three times weekly.

Common Side Effects

Common side effects include:

• Nausea
• Skin rash
• Diarrhoea
• Headache

Serious Side Effects

Co-trimoxazole can rarely cause serious reactions. These include severe skin reactions such as Stevens-Johnson syndrome (blistering, peeling, or a painful rash that spreads), blood disorders (reduced white blood cells, platelets, or red blood cells), and raised potassium levels. Seek urgent medical attention if you develop a widespread or blistering rash, unusual bruising or bleeding, or signs of infection such as persistent fever.

Monitor blood counts and renal function during prolonged courses. Risk of hyperkalaemia, especially in elderly patients or those on ACE inhibitors/ARBs. Discontinue immediately if rash develops.

Contraindicated in severe hepatic or renal impairment, blood dyscrasias, porphyria, sulphonamide allergy, first trimester of pregnancy, and infants under 6 weeks.