This sheet is about exposure to cephalexin in pregnancy and while breastfeeding. This information is based on published research studies. It should not take the place of medical care and advice from your healthcare providers.
What is cephalexin?
Cephalexin is an antibiotic medication that has been used to treat infections such as Staphylococcus aureus (Staph) and Escherichia coli (E. coli). Some brand names for cephalexin are Keflex® and Keftab®.
Sometimes when women find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take your medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy.
Having certain infections (such as a Staph or E. coli infection) during pregnancy can increase the chance for pregnancy-related problems or infections in a newborn baby. MotherToBaby has fact sheets on Staph and E. coli infections here: https://mothertobaby.org/fact-sheets/staphylococcus-aureus-pregnancy/ and https://mothertobaby.org/fact-sheets/e-coli-pregnancy/.
I take cephalexin. Can it make it harder for me to get pregnant?
Studies have not been done to see if taking cephalexin can make it harder to get pregnant. In animal studies, cephalexin did not affect fertility (ability to get pregnant).
Does taking cephalexin increase the chance of miscarriage?
Miscarriage is common and can occur in any pregnancy for many different reasons. In a study of 262 women who took cephalexin during pregnancy, there was no increase in miscarriages compared to a similar group of women who did not take cephalexin. In another study, an increased chance of miscarriage was reported with cephalexin exposure. Because miscarriage can happen for many reasons, it is hard to know whether a medication, the condition being treated, or other factors such as age or health are the cause.
Does taking cephalexin increase the chance of birth defects?
Birth defects can happen in any pregnancy for different reasons. Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect. We look at research studies to try to understand if an exposure, like cephalexin, might increase the chance of birth defects in a pregnancy.
Information on the use of cephalexin in pregnancy is limited. In a study of 262 women who took cephalexin during pregnancy, there was no increased chance for birth defects. In another study that looked at pregnancies exposed to cephalexin and medications similar to cephalexin as one group, no increased chance of birth defects was reported.
Does taking cephalexin in pregnancy increase the chance of other pregnancy-related problems?
Studies have not been done to see if cephalexin can increase the chance for pregnancy-related problems such as preterm delivery (birth before week 37) or low birth weight (weighing less than 5 pounds, 8 ounces [2500 grams] at birth).
Does taking cephalexin in pregnancy affect future behavior or learning for the child?
Studies have not been done to see if cephalexin can increase the chance of behavior or learning issues for the child.
Breastfeeding while taking cephalexin:
Cephalexin passes into breast milk in small amounts and is generally not expected to cause side effects in a breastfed child. In reports of 20 babies exposed to cephalexin through breast milk, 4 had diarrhea. There is one report of a baby getting a rash after being breastfed, due to a sensitivity to cephalexin. If you suspect the baby has any symptoms (such as diarrhea, vomiting, or rash), contact the child’s healthcare provider. Be sure to talk to your healthcare provider about all your breastfeeding questions.
If a man takes cephalexin, could it affect fertility or increase the chance of birth defects?
Studies have not been done to see if cephalexin could affect male fertility (ability to make healthy sperm) or increase the chance of birth defects. Some infections, such as Staph or E.coli, might affect male fertility. In general, men’s exposures are less likely to increase risks to a pregnancy. For more general information, please see the MotherToBaby fact sheet Paternal Exposures at https://mothertobaby.org/fact-sheets/paternal-exposures-pregnancy/.
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