Microzide 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 Microzide (Hydrochlorothiazide). The combination is generally fine at 12.5mg, 25mg, 50mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Microzide 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 Hydrochlorothiazide acts on CYP3A4 determines whether Microzide affects contraception. Most agents in Diuretics have no clinically meaningful effect on the pill at 12.5mg, 25mg, 50mg.
Practical guidance
According to the prescribing information for Hydrochlorothiazide, women on hormonal contraception should review Microzide 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 Microzide therapy is the standard mitigation.
Frequently asked questions
Will Microzide make my pill less effective? ▾
Most Diuretics medications at 12.5mg, 25mg, 50mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Hydrochlorothiazide states whether the interaction is meaningful.
Do I need a backup contraceptive on Microzide? ▾
Backup contraception is needed only when there is a documented interaction between Microzide and the contraceptive method. For most users at 12.5mg, 25mg, 50mg, no backup is required. The pharmacist confirms whether Hydrochlorothiazide interacts with hormonal contraception.
More on Microzide
- With alcoholMicrozide and alcohol — is it safe to drink?
- With foodShould Microzide be taken with food?
- Side effectsMicrozide side effects: common, rare and warning signs
- Dosage guideMicrozide dosage guide: how much to take and when
- OnsetHow fast does Microzide start working?
- DurationHow long does Microzide last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.