Does Macrobid (Nitrofurantoin) affect the efficacy of hormonal birth control?

Macrobid (Nitrofurantoin) Does Not Affect Hormonal Birth Control Effectiveness

Macrobid (nitrofurantoin) does not reduce the effectiveness of hormonal birth control methods and no special precautions are needed when using these medications together. 1

Evidence on Antibiotics and Hormonal Contraception

• Most broad-spectrum antibiotics, including nitrofurantoin (Macrobid), do not affect the contraceptive effectiveness of hormonal birth control methods 2
• A systematic review specifically examining non-rifamycin antibiotics (including nitrofurantoin) found no evidence of reduced hormonal contraceptive effectiveness when used concurrently 1
• Unlike rifampin (which does decrease contraceptive effectiveness), nitrofurantoin does not induce liver enzymes that metabolize hormonal contraceptives 2

Clinical Guidelines on Antibiotic-Contraceptive Interactions

• The CDC and American Academy of Pediatrics explicitly state that most broad-spectrum antibiotics do not affect hormonal contraceptive effectiveness 2
• Current guidelines specifically note: "Most broad-spectrum antibiotics (rifampin is an exception) do not affect the contraceptive effectiveness of COCs" 2
• Only rifamycin antibiotics (like rifampin) are listed in clinical guidelines as medications that decrease hormonal contraceptive efficacy 2

Special Considerations with Nitrofurantoin

• While nitrofurantoin can have potential adverse effects (pulmonary and hepatic toxicity in rare cases), these are not related to contraceptive interactions 2
• The most common side effects of nitrofurantoin are gastrointestinal disturbances and skin rash, which do not impact contraceptive effectiveness 2
• When treating UTIs in women using hormonal contraception, nitrofurantoin can be prescribed without concerns about reduced contraceptive efficacy 1

What To Do If Vomiting or Diarrhea Occurs

While nitrofurantoin itself doesn't affect hormonal contraception, severe gastrointestinal symptoms could potentially impact absorption:

• If vomiting occurs within 24 hours of taking a hormonal pill, no additional action is needed 2
• If vomiting or diarrhea continues for 24-48 hours, continue taking pills but use backup contraception until hormonal pills have been taken for 7 consecutive days after symptoms resolve 2
• If vomiting or diarrhea continues for more than 48 hours, follow extended illness protocols for hormonal contraception 2

Conclusion for Clinical Practice

When prescribing Macrobid (nitrofurantoin) to patients on hormonal contraception:

• No additional contraceptive measures are needed 2, 1
• No adjustment to hormonal contraceptive dosing is required 2
• Patient counseling should focus on adherence to both medications as prescribed 2

This guidance applies to all forms of hormonal contraception, including combined oral contraceptives, contraceptive patches, vaginal rings, and progestin-only methods 1.