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 Trimethoprim.
Blood disorders: The presence of sore throat, fever, pale skin, rash, or jaundice (yellowing of the skin) may be early signs of rare but serious blood disorders. If you develop any of these symptoms after starting trimethoprim, contact your doctor as soon as possible.
Folic acid levels: Trimethoprim affects how the body uses folic acid, a nutrient necessary for the formation of red blood cells. If you have a folic acid deficiency, discuss with your doctor how Trimethoprim may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Trimethoprim, and whether any special monitoring is needed.
Kidney function: Kidney Disease or reduced kidney function may cause Trimethoprim to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how Trimethoprim may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Trimethoprim, and whether any special monitoring is needed.
Liver function: Liver disease or reduced liver function may cause Trimethoprim to build up in the body, causing side effects. If you have reduced liver function or liver disease, discuss with your doctor how Trimethoprim may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Trimethoprim, and whether any special monitoring is needed.
Pregnancy: When trimethoprim is taken during pregnancy, it crosses the placenta and may affect the unborn baby. Trimethoprim should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Trimethoprim, contact your doctor immediately.
Breast-feeding: Trimethoprim passes into breast milk. If you are a breast-feeding mother and are taking trimethoprim, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using trimethoprim for infants younger than 2 months of age have not been established. The effectiveness of using trimethoprim alone (i.e., not in combination with other antibiotics) has not been established for children under 12 years of age.