Sulfamethoxazole

The Basics

What is Sulfamethoxazole?

Treats infections like chronic bronchitis, urinary tract infections, and acute ear infections.

Brand names for Sulfamethoxazole

Bactrim

How Sulfamethoxazole is classified

Anti-Infective Agents, Antibacterial Agents, Sulfonamides

Sulfamethoxazole During Pregnancy

Sulfamethoxazole pregnancy category

Category N/ANote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.

What we know about taking Sulfamethoxazole while pregnant

BACTRIM may cause fetal harm if administered to a pregnant woman. Some epidemiologic studies suggest that exposure to BACTRIM during pregnancy may be associated with an increased risk of congenital malformations, particularly neural tube defects, cardiovascular abnormalities, urinary tract defects, oral clefts, and club foot [see Human Data]. One of 3 rat studies showed cleft palate at doses approximately 5 times the recommended human dose on a body surface area basis; the other 2 studies did not show teratogenicity at similar doses. Studies in pregnant rabbits showed increased fetal loss at approximately 6 times the human dose on a body surface area basis [see Animal Data]. The estimated background risk of major birth defects and miscarriages for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. Advise pregnant women of the potential harm of BACTRIM to the fetus [see Clinical Considerations]. Clinical Considerations Disease-associated Maternal and/or Embryo/Fetal Risk Urinary tract infection in pregnancy is associated with adverse perinatal outcomes such as preterm birth, low birth weight, and pre-eclampsia, and increased mortality to the pregnant woman. P. jirovecii pneumonia in pregnancy is associated with preterm birth and increased morbidity and mortality for the pregnant woman. BACTRIM should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Taking Sulfamethoxazole While Breastfeeding

What are recommendations for lactation if you're taking Sulfamethoxazole?

With healthy, fullterm infants it appears acceptable to use sulfamethoxazole during breastfeeding after the newborn period. The time of greatest risk for hemolysis in fullterm newborns without glucose-6-phosphate dehydrogenase (G6PD) deficiency might be as short as 8 days after birth.[1] Until further data are accumulated, alternate agents should probably be used in jaundiced, ill, stressed or premature infants, because of the risk of bilirubin displacement and kernicterus. Sulfamethoxazole should be avoided while breastfeeding a G6PD deficient infant.[2]

Maternal / infant drug levels

With healthy, fullterm infants it appears acceptable to use sulfamethoxazole during breastfeeding after the newborn period. The time of greatest risk for hemolysis in fullterm newborns without glucose-6-phosphate dehydrogenase (G6PD) deficiency might be as short as 8 days after birth.[1] Until further data are accumulated, alternate agents should probably be used in jaundiced, ill, stressed or premature infants, because of the risk of bilirubin displacement and kernicterus. Sulfamethoxazole should be avoided while breastfeeding a G6PD deficient infant.[2]

Possible effects of Sulfamethoxazole on milk supply

Relevant published information was not found as of the revision date.

Possible alternatives to Sulfamethoxazole

Sulfisoxazole, Trimethoprim-Sulfamethoxazole.