Ovestin 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 Ovestin (Estriol). The combination is generally fine at 0.1%, 0.5mg, 1mg, 2mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Ovestin 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 Estriol acts on CYP3A4 determines whether Ovestin affects contraception. Most agents in Hormones and Birth Control have no clinically meaningful effect on the pill at 0.1%, 0.5mg, 1mg, 2mg.
Practical guidance
According to the prescribing information for Estriol, women on hormonal contraception should review Ovestin 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 Ovestin therapy is the standard mitigation.
Frequently asked questions
Will Ovestin make my pill less effective? ▾
Most Hormones and Birth Control medications at 0.1%, 0.5mg, 1mg, 2mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Estriol states whether the interaction is meaningful.
Do I need a backup contraceptive on Ovestin? ▾
Backup contraception is needed only when there is a documented interaction between Ovestin and the contraceptive method. For most users at 0.1%, 0.5mg, 1mg, 2mg, no backup is required. The pharmacist confirms whether Estriol interacts with hormonal contraception.
More on Ovestin
- With alcoholOvestin and alcohol — is it safe to drink?
- With foodShould Ovestin be taken with food?
- Side effectsOvestin side effects: common, rare and warning signs
- Dosage guideOvestin dosage guide: how much to take and when
- OnsetHow fast does Ovestin start working?
- DurationHow long does Ovestin last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.