From the Guidelines
Cefalexin is safe to use during early pregnancy, with no adverse effects reported, and can be prescribed when necessary for treating bacterial infections. The use of cefalexin in pregnancy is supported by evidence from studies in non-HS patients, which suggests that it is safe, along with azithromycin and clindamycin, with no adverse effects reported 1. When prescribing cefalexin during early pregnancy, the recommended dosage is typically 250-500 mg taken orally every 6 hours, or 500-1000 mg every 12 hours, for 7-14 days depending on the infection being treated.
- Key considerations for the use of cefalexin in early pregnancy include:
- Completing the full course of antibiotics as prescribed to ensure the infection is completely cleared
- Monitoring for common side effects such as diarrhea, nausea, and vomiting
- Being aware of the potential for severe side effects or allergic reactions, such as rash, itching, or difficulty breathing, and contacting a healthcare provider immediately if these occur
- It is also important to note that untreated bacterial infections during pregnancy can pose greater risks to both mother and baby than the potential risks of the antibiotic, making the use of cefalexin a reasonable choice when necessary 1.
From the FDA Drug Label
Pregnancy Teratogenic Effects Pregnancy category B Reproduction studies have been performed on mice and rats using oral doses of cephalexin monohydrate 0.6 and 1. 5 times the maximum daily human dose (66 mg/kg/day) based upon mg/m2, and have revealed no harm to the fetus. There are, however, no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed
Cefalexin use in early pregnancy should be done with caution. The drug is classified as Pregnancy category B, and while animal studies have shown no harm to the fetus, there are no adequate and well-controlled studies in pregnant women. Therefore, cefalexin should only be used during pregnancy if clearly needed 2.
From the Research
Cefalexin Use in Early Pregnancy
- Cefalexin is a type of antibiotic that belongs to the class of cephalosporins 3.
- According to a study published in 1998, cefalexin was used by 1.0% of pregnant women, with the majority of women using penicillin (14.5%) or other types of antibiotics 3.
- The use of antibiotics during pregnancy, including cefalexin, has been associated with a lower mean birth weight compared to untreated groups 3.
- A review of antibiotic use in pregnancy published in 2015 noted that cephalosporins, including cefalexin, are generally considered safe and effective in pregnancy 4.
- Another study published in 2020 discussed the pharmacokinetics of cefazolin, a related cephalosporin, during pregnancy, highlighting the importance of considering the deep compartments of the fetal and amniotic fluid when administering antimicrobial prophylaxis 5.
Safety and Efficacy of Cefalexin in Pregnancy
- A review of acne treatment during pregnancy published in 2013 recommended the use of topical medications as first-line treatment, with oral agents such as cephalexin considered as second-line treatment 6.
- A more recent review published in 2024 discussed the management of acne during pregnancy, including the use of cephalexin as a systemic treatment option 7.
- The safety and efficacy of cefalexin in pregnancy have not been extensively studied, but available data suggest that it is generally considered safe and effective when used appropriately 4, 6, 7, 3.