Furosemide (Lasix) 40mg: Drug Names, Pregnancy, and Lactation Information
Trade and Generic Names
Furosemide is the generic name, and Lasix is the most common trade name for this loop diuretic medication. 1
Pregnancy Risk Factors
Furosemide should only be used during pregnancy if the potential benefit clearly justifies the potential risk to the fetus, as it has caused unexplained maternal deaths and abortions in animal studies. 1
Critical Pregnancy Considerations:
Animal toxicity data: Furosemide caused unexplained maternal deaths and abortions in rabbits at doses as low as 2 times the maximum recommended human dose of 600 mg/day 1
Fetal effects documented in animal studies: Increased incidence and severity of hydronephrosis (distention of the renal pelvis and ureters) in fetuses from treated animals compared to controls 1
No adequate human studies: There are no adequate and well-controlled studies in pregnant women 1
Fetal growth monitoring required: Treatment during pregnancy requires monitoring of fetal growth because of the potential for higher birth weights 1
Clinical Context for Use in Pregnancy:
Limited appropriate indications: Furosemide has been used safely in pregnancy complicated by renal or cardiac failure, but diuretics are generally controversial in pregnancy 2
Contraindicated in pre-eclampsia: Diuretics reduce plasma volume expansion and are contraindicated when utero-placental circulation perfusion is already reduced in pre-eclampsia with fetal growth retardation 2
Mechanism of concern: Diuretics reduce plasma volume expansion, raising concern that their use might promote the occurrence of pre-eclampsia 2
Preferred diuretic if needed: If a diuretic is needed during pregnancy, a thiazide should be chosen over furosemide 2
Lactation Considerations
Furosemide appears in breast milk and may inhibit lactation; caution should be exercised when administering to nursing mothers. 1
Specific Breastfeeding Guidance:
Milk production concerns: Diuretics, including furosemide, may reduce milk volume and potentially suppress lactation, particularly at higher doses 3
Not a first-line agent: Diuretics should be considered alternative agents rather than first-line therapy during breastfeeding 3
Preferred alternatives exist: First-line agents for postpartum hypertension regardless of breastfeeding status include nifedipine, amlodipine, enalapril, and labetalol 3
Clinical decision-making: Consider withholding antihypertensive medication during the breastfeeding period if clinically appropriate, with close blood pressure monitoring 3
If Furosemide Must Be Used During Breastfeeding:
Use lowest effective dose to minimize impact on milk production 3
Monitor infant closely for signs of dehydration 3
Monitor milk production and infant weight gain 3
Single dose postpartum: A single intravenous dose of furosemide is commonly given after delivery to manage auto-transfusion of blood from the lower limbs and contracted uterus 2
Important Caveats:
The European Heart Journal guidelines note that furosemide (and hydrochlorothiazide and spironolactone) may reduce milk production and are generally not preferred in breastfeeding women. 2 This reinforces that while furosemide can be used when maternal cardiovascular benefit is the primary consideration, safer alternatives should be prioritized for routine postpartum hypertension management in breastfeeding mothers.