Lasix with the birth control pill
Many women of reproductive age take a combined or progestogen-only oral contraceptive while also using a chronic medication such as Lasix (Furosemide). The combination is generally fine at 20mg, 40mg, 100mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Lasix can affect contraceptive efficacy
Combined and progestogen-only contraceptives are metabolised through CYP3A4. Strong CYP3A4 inducers (some antiepileptics, rifampicin, St John's Wort) lower contraceptive plasma levels and reduce efficacy. Whether Furosemide acts on CYP3A4 determines whether Lasix affects contraception. Most agents in Diuretics have no clinically meaningful effect on the pill at 20mg, 40mg, 100mg.
Practical guidance
According to the prescribing information for Furosemide, women on hormonal contraception should review Lasix with the prescribing pharmacist or doctor. Where an interaction is documented, additional barrier contraception or switching to a non-oral method (IUD, implant) for the duration of Lasix therapy is the standard mitigation.
Frequently asked questions
Will Lasix make my pill less effective? ▾
Most Diuretics medications at 20mg, 40mg, 100mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Furosemide states whether the interaction is meaningful.
Do I need a backup contraceptive on Lasix? ▾
Backup contraception is needed only when there is a documented interaction between Lasix and the contraceptive method. For most users at 20mg, 40mg, 100mg, no backup is required. The pharmacist confirms whether Furosemide interacts with hormonal contraception.
More on Lasix
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.