Antibiotics Safe in Pregnancy

First-Line Safe Antibiotics

• The American Academy of Dermatology recommends penicillins, such as amoxicillin, and first-generation cephalosporins, such as cephalexin, as the safest first-line antibiotics during pregnancy, with extensive human data showing no teratogenic effects at therapeutic doses 1, 2
• Amoxicillin is classified as Category A/B and is compatible throughout all trimesters and during breastfeeding, according to the European Respiratory Society 1, 3
• Cephalexin has moderate-quality evidence supporting safety throughout pregnancy with no demonstrated fetal harm, as stated by the American Academy of Dermatology 2, 4
• Amoxicillin-clavulanate is compatible during pregnancy, but should be avoided in women at risk of preterm delivery due to a very low risk of necrotizing enterocolitis in the fetus, as recommended by the European Respiratory Society 1, 3
• Piperacillin-tazobactam is explicitly listed as "compatible" for use during pre-conception and first trimester, with all penicillins considered low risk based on decades of clinical experience, according to the European Respiratory Society 1, 5

Antibiotics to AVOID

• The American Academy of Dermatology and the European Respiratory Society recommend avoiding doxycycline and tetracyclines during pregnancy due to tooth discoloration, transient bone growth suppression, and potential maternal fatty liver of pregnancy 1, 2, 3, 6
• Co-trimoxazole should be avoided, especially during the first trimester, due to increased risk of preterm birth, low birthweight, kernicterus, hyperbilirubinemia, and fetal hemolytic anemia, as stated by the European Respiratory Society and the American Academy of Dermatology 1, 2, 3, 6

Special Considerations by Trimester

• The European Respiratory Society recommends avoiding co-trimoxazole and trimethoprim during the first trimester due to neural tube defect risk, and supplementing with 5 mg/day folic acid if necessary 1, 3
• Sulfonamides should be avoided during the first trimester due to association with hyperbilirubinemia, as recommended by the European Respiratory Society 1, 3
• Tetracyclines are strictly contraindicated after week 5 of pregnancy, according to the European Respiratory Society 1, 3

Breastfeeding Considerations

• Most systemic antibiotics are present in breast milk and could cause falsely negative cultures in febrile infants or gastroenteritis due to altered intestinal flora, as stated by the European Respiratory Society 3
• Co-trimoxazole is compatible with breastfeeding in healthy term babies, but should be avoided in babies who are G6PD deficient, jaundiced, or premature, according to the European Respiratory Society 1, 3

Safe Antibiotics in Pregnancy

First-Line Safe Antibiotics

• The American Academy of Dermatology recommends cephalexin as a safe first-line antibiotic during pregnancy, with moderate-quality evidence supporting its safety throughout pregnancy and no demonstrated fetal harm 7
• Azithromycin and erythromycin are considered safe alternatives for penicillin-allergic patients, though preliminary data on azithromycin remain insufficient for routine recommendation, according to the American Academy of Dermatology and the Centers for Disease Control and Prevention 7, 8
• Erythromycin base 500 mg orally four times daily for 7 days is a recommended regimen for pregnant women with chlamydial infections, as suggested by the Centers for Disease Control and Prevention 8
• Clindamycin has moderate evidence supporting its safety in pregnancy, with no significant risks of congenital anomalies or preterm delivery, according to the American Academy of Dermatology 7

Antibiotics to Avoid

• Co-trimoxazole (TMP-SMX) should be avoided, especially during the first trimester, due to increased risk of preterm birth, low birthweight, kernicterus, hyperbilirubinemia, and fetal hemolytic anemia, as recommended by the American Academy of Dermatology 7
• Ofloxacin is specifically contraindicated for pregnant women, as stated by the Centers for Disease Control and Prevention 8
• Erythromycin estolate is contraindicated during pregnancy due to drug-related hepatotoxicity, according to the Centers for Disease Control and Prevention 8

Special Considerations

• The Centers for Disease Control and Prevention and the World Health Organization endorse rifampin as a first-line treatment for tuberculosis in pregnancy, supporting its safety in select pregnant patients with severe hidradenitis suppurativa, in combination with clindamycin, as recommended by the American Academy of Dermatology 7
• Ertapenem may be considered in select recalcitrant cases, as animal studies showed no teratogenic evidence, according to the American Academy of Dermatology 7

Safe IV Antibiotics in Pregnancy

First-Line Safe IV Antibiotics

• The Centers for Disease Control and Prevention recommends Ampicillin for intrapartum prophylaxis, particularly for Group B Streptococcus, with demonstrated efficacy and safety when administered intravenously 9
• The Centers for Disease Control and Prevention recommends Cefazolin as a suitable alternative for intrapartum prophylaxis, with a relatively narrow spectrum of activity and high intra-amniotic concentrations 9
• The American Academy of Pediatrics recommends Ceftriaxone for neonatal gonococcal ophthalmia, with a dose of 25-50 mg/kg IV, and is safe throughout pregnancy 10

Antibiotics to Avoid

• The American College of Obstetricians and Gynecologists recommends avoiding Tetracyclines and doxycycline after the fifth week of pregnancy due to tooth discoloration, transient bone growth suppression, and potential maternal fatty liver of pregnancy 10

Specific Clinical Scenarios

• The Centers for Disease Control and Prevention recommends Penicillin G for Group B Streptococcus prophylaxis, with a dose of 5 million units IV initially, then 2.5-3 million units IV every 4 hours until delivery 9
• The Centers for Disease Control and Prevention recommends Ampicillin as an acceptable alternative for Group B Streptococcus prophylaxis, with proven efficacy 9
• The Centers for Disease Control and Prevention recommends Cefazolin for penicillin-allergic patients without high risk of anaphylaxis for Group B Streptococcus prophylaxis 9
• The American Academy of Pediatrics recommends Ceftriaxone for gonococcal infections, with a dose of 250 mg IM single dose, and pregnant women should not be treated with doxycycline, quinolones, or tetracyclines 10

Safe Antibiotics in Pregnancy

Antibiotics to Avoid in Pregnancy

• The CDC notes that although tetracyclines are not recommended during pregnancy, their use may be indicated for life-threatening illness and doxycycline might be used for a short time before six months of gestation, as adverse effects on developing teeth and bones are dose-related 11
• For bioterrorism-related anthrax exposure in pregnant women, ciprofloxacin or doxycycline may be used due to the life-threatening nature of the illness, as recommended by the American family physician 11

Guideline Summary: Antibiotic Use at 16 Weeks Gestation

1. First‑Line Beta‑Lactam Antibiotics (Safe)

• Cephalexin is supported by moderate‑quality evidence showing no fetal harm when used throughout pregnancy. American Academy of Dermatology recommends it as a safe first‑generation cephalosporin. 12
• Amoxicillin‑clavulanate is compatible with pregnancy but should be avoided in women at imminent risk of preterm delivery because of a very low theoretical risk of necrotizing enterocolitis in preterm infants. European Respiratory Society notes this precaution. 13
• Piperacillin‑tazobactam (IV) is explicitly listed as compatible during pregnancy; all penicillins are considered low‑risk based on decades of clinical experience. European Respiratory Society endorses its use when IV therapy is required. 13

2. Macrolides (Second‑Line for Penicillin Allergy)

• Azithromycin is regarded as safe with moderate‑quality evidence, but it should be limited to short‑term acute treatment rather than prolonged courses. American Academy of Dermatology advises this restriction. 12
• Erythromycin base (not the estolate formulation) is safe throughout pregnancy; the estolate form must be avoided because of a risk of maternal hepatotoxicity. European Respiratory Society provides this guidance. 13

3. Other Safe Antibiotic Options

• Clindamycin has moderate‑quality evidence indicating no significant increase in congenital anomalies or preterm delivery. American Academy of Dermatology recommends it when beta‑lactams are unsuitable. 12
• Metronidazole may be used when no safer alternatives exist; however, some guidelines advise caution because of a potential association with low birth‑weight infants. Both European Respiratory Society and American Academy of Dermatology note this consideration. [13][12]

4. Antibiotics That Must Be Avoided (Contraindicated)

• Tetracyclines (including doxycycline) are strictly contraindicated after gestational week 5 due to risks of fetal tooth discoloration, transient bone‑growth suppression, and maternal fatty‑liver changes. European Respiratory Society and American Academy of Dermatology concur. [13][12]

5. Strongly Discouraged Antibiotics

• Trimethoprim‑sulfamethoxazole (co‑trimoxazole) should be avoided, especially in the first trimester, because of increased risks of preterm birth, low birth‑weight, kernicterus, hyperbilirubinemia, and fetal hemolytic anemia. European Respiratory Society and American Academy of Dermatology highlight these hazards. [13][12]
• Aminoglycosides (e.g., gentamicin, tobramycin) should be reserved for life‑threatening maternal infections only, due to potential eighth cranial nerve toxicity and nephrotoxicity in the fetus. European Respiratory Society recommends this restriction. 13

6. Special Clinical Considerations

• When co‑trimoxazole is absolutely necessary, supplementation with 5 mg/day folic acid is advised to mitigate neural‑tube‑defect risk. European Respiratory Society provides this recommendation. 13
• Carbapenems (ertapenem, meropenem) may be used as first‑line agents in patients with a documented history of resistance to third‑generation cephalosporins. American Academy of Dermatology supports this approach. 12
• Antibiotics present in breast milk can lead to falsely negative cultures in febrile infants being evaluated, necessitating careful interpretation of microbiologic results. European Respiratory Society notes this pitfall. 13