Prometrium 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 Prometrium (Progesterone). The combination is generally fine at 100mg, 200mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Prometrium 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 Progesterone acts on CYP3A4 determines whether Prometrium affects contraception. Most agents in Hormones and Birth Control have no clinically meaningful effect on the pill at 100mg, 200mg.
Practical guidance
According to the prescribing information for Progesterone, women on hormonal contraception should review Prometrium 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 Prometrium therapy is the standard mitigation.
Frequently asked questions
Will Prometrium make my pill less effective? ▾
Most Hormones and Birth Control medications at 100mg, 200mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Progesterone states whether the interaction is meaningful.
Do I need a backup contraceptive on Prometrium? ▾
Backup contraception is needed only when there is a documented interaction between Prometrium and the contraceptive method. For most users at 100mg, 200mg, no backup is required. The pharmacist confirms whether Progesterone interacts with hormonal contraception.
More on Prometrium
- With alcoholPrometrium and alcohol — is it safe to drink?
- With foodShould Prometrium be taken with food?
- Side effectsPrometrium side effects: common, rare and warning signs
- Dosage guidePrometrium dosage guide: how much to take and when
- OnsetHow fast does Prometrium start working?
- DurationHow long does Prometrium last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.