What antibiotic is safe for a breastfeeding mother with a urinary tract infection (UTI)?

From the Guidelines

Breastfeeding mothers with UTIs can safely use antibiotics such as amoxicillin, cefuroxime, or azithromycin, as they are considered compatible with breastfeeding 1. When choosing an antibiotic for a breastfeeding mother with a UTI, it's essential to consider the safety of the medication for the nursing infant.

• Amoxicillin is a commonly used antibiotic for UTIs, and it is classified as category B, indicating that it is likely safe for use during breastfeeding 1.
• Cefuroxime is another option, which is also classified as category B, and human data indicate that it is not teratogenic at usual therapeutic doses 1.
• Azithromycin is a macrolide antibiotic that is considered probably safe for use during breastfeeding, although there is a very low risk of hypertrophic pyloric stenosis in infants exposed to macrolides during the first 13 days of breastfeeding 1. It's crucial to note that most systemic antibiotics will be present in breast milk, which could cause falsely negative cultures in febrile infants or produce gastroenteritis due to alteration of intestinal flora 1. The choice of antibiotic depends on the specific bacteria causing the infection, local resistance patterns, and the mother's medication history.
• The typical dosing for amoxicillin is 500mg three times daily for 7 days.
• Cefuroxime is usually given as 250-500mg twice daily for 7-10 days.
• Azithromycin is typically prescribed as a single dose of 1g or 500mg daily for 3-5 days. Breastfeeding mothers should complete the full course of antibiotics even if symptoms improve quickly and stay well-hydrated to help flush bacteria from the urinary tract. If the mother experiences fever, back pain, or worsening symptoms while on antibiotics, she should contact her healthcare provider immediately.

From the FDA Drug Label

Both sulfamethoxazole and trimethoprim distribute to sputum, vaginal fluid, and middle ear fluid; trimethoprim also distributes to bronchial secretions, and both pass the placental barrier and are excreted in human milk

• Trimethoprim-sulfamethoxazole is excreted in human milk, however, the FDA label does not provide explicit information on the safety of this antibiotic for breastfeeding mothers with UTI.
• The FDA label for amoxicillin states that penicillins have been shown to be excreted in human milk and caution should be exercised when amoxicillin is administered to a nursing woman.
• Based on the available information, neither trimethoprim-sulfamethoxazole nor amoxicillin can be considered completely safe for breastfeeding mothers with UTI without exercising caution 2 3.
• A conservative clinical decision would be to consult the FDA label and other reliable sources for the most up-to-date information and consider alternative antibiotics that are known to be safe for breastfeeding mothers.

From the Research

Antibiotic Safety for Breastfeeding Mothers with UTI

• The use of nitrofurantoin in breastfeeding mothers is generally considered safe, as only small amounts transfer into the breast milk 4.
• However, there is a risk of hemolytic anemia in all newborns exposed to nitrofurantoin, especially in infants with glucose-6-phosphate dehydrogenase deficiency 4.
• Some studies suggest that nitrofurantoin be avoided in infants younger than 1 month, but if an alternative antibiotic is not available, the use of nitrofurantoin would not be a reason to avoid breastfeeding 4.
• Nitrofurantoin has been recommended as a first-line antibiotic for the empiric treatment of uncomplicated cystitis in otherwise healthy women, including those who are breastfeeding 5, 6, 7.
• The advantages of nitrofurantoin include its high urinary concentrations and minimal toxicity, making it a potential treatment option for patients with uncomplicated urinary tract infection due to resistant organisms 7.

Considerations for Nitrofurantoin Use

• Nitrofurantoin is contraindicated in the last three months of pregnancy and in patients suffering from renal impairment of each degree 5.
• The use of nitrofurantoin has been shown to be accompanied by numerous adverse drug effects, including serious side effects such as pulmonary reactions and polyneuropathy, which mainly occur in long-term use 5.
• Despite these concerns, nitrofurantoin has been recommended for the re-infection prophylaxis of recurrent uncomplicated urinary tract infections in Germany and several other countries 5.