Sulfamethoxazole/Trimethoprim, also called co-trimoxazole, is a combination of two antibiotics prescribed to treat a variety of bacterial infections including bladder and urinary tract infections; ear infections; lung infections, particularly pneumonia caused by Pneumocystis jiroveci; nocardiosis; and toxoplasmosis.
Common side effects include:
- Anorexia (loss of appetite)
These are usually mild and non-life-threatening, but you should immediately consult your doctor if they become persistent or more severe.
More serious reactions include:
- Blood in the urine
- Change in color
- Change in frequency or amount; blood or mucus in the stool
- Abdominal pain or cramping
- Mental changes such as mood swings
- Persistent sore throat or cough
- Goiter (lump in the neck)
- Low blood sugar, indicated by shakiness, dizziness, blurred vision, unusual hunger; fever; pallor; and joint pain.
- You may also experience mild to severe allergic reactions which manifest as itching, swelling, skin rash, blisters or severe peeling of the skin (Stevens-Johnson syndrome).
If you experience these symptoms, you should promptly contact or doctor. Side effects that require immediate medical attention include confusion, bleeding issues, neck stiffness, persistent headache, seizures, breathing trouble, unusual fatigue and yellowing of the eyes or skin. Take extra care and discuss use of this medication with your doctor if you have a blood disorder, liver or kidney disease, asthma, severe allergies or are pregnant or nursing.
Also avoid prolonged exposure to sunlight while on co-trimoxazole as it may make your skin more sensitive to sun exposure.