You should not use Bactrim if you have severe liver disease, kidney disease that is not being monitored, anemia caused by folic acid deficiency, if you take dofetilide, or if you have had low platelets caused by using trimethoprim or a sulfa drug.
You should not take sulfamethoxazole and trimethoprim if you are pregnant or breastfeeding.
Before taking this medicine
You should not use Bactrim if you are allergic to sulfamethoxazole or trimethoprim, or if you have:
severe liver disease;
kidney disease that is not being treated or monitored;
anemia (low red blood cells) caused by folic acid deficiency;
a history of low blood platelets after taking trimethoprim or any sulfa drug; or
if you take dofetilide (Tikosyn).
Do not use Bactrim if you are pregnant. This medicine could harm the unborn baby or cause birth defects. Use effective birth control, and tell your doctor if you are pregnant or become pregnant.
Do not breastfeed while using this medicine.
This medicine should not be given to a child younger than 2 months old.
To make sure Bactrim is safe for you, tell your doctor if you have:
kidney or liver disease;
a folate (folic acid) deficiency;
asthma or severe allergies;
a thyroid disorder;
malnourishment;
alcoholism;
high levels of potassium in your blood;
porphyria, or glucose-6-phosphate dehydrogenase (G6PD) deficiency; or
if you use a blood thinner (such as warfarin) and you have routine "INR" or prothrombin time tests.
