Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Antibiotic-related diarrhea: As with other antibiotics, trimethoprim – sulfamethoxazole can cause a severe form of diarrhea associated with a condition known as pseudomembranous colitis. If you develop severe diarrhea while taking (or within a few weeks of taking) this medication, contact your doctor.
Drowsiness/reduced alertness: Trimethoprim – sulfamethoxazole may cause some people to become dizzy. Determine your response to this medication before engaging in potentially dangerous activities such as driving or operating machinery.
Kidney function: Kidney disease or reduced kidney function may cause this medication to build up in the body, causing side effects. Trimethoprim – sulfamethoxazole may also cause decreased kidney function. If you have reduced kidney function or kidney disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Medical conditions: If you have liver or kidney damage, urinary obstruction, blood disorders, allergies, or bronchial asthma, discuss with your doctor the benefits and risks of this medication.
Symptoms such as rash, sore throat, fever, pallor, difficulty breathing, or jaundice (yellowing of eyes or skin) may be early indications of rare but severe reactions. Anyone experiencing these symptoms after starting this medication should contact their doctor immediately.
Other infections: The prolonged or repeated use of antibiotics may occasionally result in organisms not killed by the antibiotic to overgrow. This may result in conditions such as yeast infections. If you experience new symptoms of infection or find that the infection is not improving with correct use of this medication, contact your doctor.
Sensitivity to sunlight: This medication may increase the sensitivity of the skin to sunlight, increasing the risk of sunburn. If you notice any unusual skin rash or peeling, contact your doctor immediately.
Skin rash: Trimethoprim – sulfamethoxazole may cause skin rash or itchiness with or without a rash. Rarely, people taking trimethoprim – sulfamethoxazole experience a severe skin reaction that can be life-threatening. If you experience a rash that gets worse, develops into blisters or sores on the lips or eyes, or covers a large area of the body, contact your doctor immediately.
Pregnancy: This medication should not be used during pregnancy unless, in the opinion of your doctor, the benefits outweigh the risks. Pregnant women who take this medication should consider taking supplemental folic acid.
Breast-feeding: Both trimethoprim and sulfamethoxazole pass into breast milk. If you are a breast-feeding mother and are taking trimethoprim – sulfamethoxazole, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: This medication is not recommended for children younger than 2 months of age.
Seniors: Seniors may be at increased risk of developing side effects when taking this medication. Lower doses may be required.