Tamiflu 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 Tamiflu (Oseltamivir). The combination is generally fine at 30mg, 45mg, 75mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Tamiflu 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 Oseltamivir acts on CYP3A4 determines whether Tamiflu affects contraception. Most agents in Antiviral Medications have no clinically meaningful effect on the pill at 30mg, 45mg, 75mg.
Practical guidance
According to the prescribing information for Oseltamivir, women on hormonal contraception should review Tamiflu 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 Tamiflu therapy is the standard mitigation.
Frequently asked questions
Will Tamiflu make my pill less effective? ▾
Most Antiviral Medications medications at 30mg, 45mg, 75mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Oseltamivir states whether the interaction is meaningful.
Do I need a backup contraceptive on Tamiflu? ▾
Backup contraception is needed only when there is a documented interaction between Tamiflu and the contraceptive method. For most users at 30mg, 45mg, 75mg, no backup is required. The pharmacist confirms whether Oseltamivir interacts with hormonal contraception.
More on Tamiflu
- With alcoholTamiflu and alcohol — is it safe to drink?
- With foodShould Tamiflu be taken with food?
- Side effectsTamiflu side effects: common, rare and warning signs
- Dosage guideTamiflu dosage guide: how much to take and when
- OnsetHow fast does Tamiflu start working?
- DurationHow long does Tamiflu last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.