Thiazide-like diuretic
Chlorthalidone 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 Chlorthalidone (Chlorthalidone). The combination is generally fine at 15mg, 25mg, 50mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Chlorthalidone 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 Chlorthalidone acts on CYP3A4 determines whether Chlorthalidone affects contraception. Most agents in Thiazide-like diuretic have no clinically meaningful effect on the pill at 15mg, 25mg, 50mg.
Practical guidance
According to the prescribing information for Chlorthalidone, women on hormonal contraception should review Chlorthalidone 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 Chlorthalidone therapy is the standard mitigation.
Frequently asked questions
Will Chlorthalidone make my pill less effective? ▾
Most Thiazide-like diuretic medications at 15mg, 25mg, 50mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Chlorthalidone states whether the interaction is meaningful.
Do I need a backup contraceptive on Chlorthalidone? ▾
Backup contraception is needed only when there is a documented interaction between Chlorthalidone and the contraceptive method. For most users at 15mg, 25mg, 50mg, no backup is required. The pharmacist confirms whether Chlorthalidone interacts with hormonal contraception.
Products containing Chlorthalidone
More on Chlorthalidone
- With alcoholChlorthalidone and alcohol — is it safe to drink?
- With foodShould Chlorthalidone be taken with food?
- Side effectsChlorthalidone side effects: common, rare and warning signs
- Dosage guideChlorthalidone dosage guide: how much to take and when
- OnsetHow fast does Chlorthalidone start working?
- DurationHow long does Chlorthalidone last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.