Nucleoside antiviral prodrug
Valacyclovir 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 Valacyclovir (Valacyclovir). The combination is generally fine at 500mg, 1000mg, but a small number of medications can reduce contraceptive efficacy meaningfully and need either a backup method or a switch.
How Valacyclovir 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 Valacyclovir acts on CYP3A4 determines whether Valacyclovir affects contraception. Most agents in Nucleoside antiviral prodrug have no clinically meaningful effect on the pill at 500mg, 1000mg.
Practical guidance
According to the prescribing information for Valacyclovir, women on hormonal contraception should review Valacyclovir 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 Valacyclovir therapy is the standard mitigation.
Frequently asked questions
Will Valacyclovir make my pill less effective? ▾
Most Nucleoside antiviral prodrug medications at 500mg, 1000mg do not affect oral contraceptive efficacy. The exceptions are CYP3A4-inducing drugs and a small number of others. The prescribing information for Valacyclovir states whether the interaction is meaningful.
Do I need a backup contraceptive on Valacyclovir? ▾
Backup contraception is needed only when there is a documented interaction between Valacyclovir and the contraceptive method. For most users at 500mg, 1000mg, no backup is required. The pharmacist confirms whether Valacyclovir interacts with hormonal contraception.
Products containing Valacyclovir
More on Valacyclovir
- With alcoholValacyclovir and alcohol — is it safe to drink?
- With foodShould Valacyclovir be taken with food?
- Side effectsValacyclovir side effects: common, rare and warning signs
- Dosage guideValacyclovir dosage guide: how much to take and when
- OnsetHow fast does Valacyclovir start working?
- DurationHow long does Valacyclovir last?
The information on this website is provided for reference and educational purposes only. It does not replace consultation with a qualified healthcare professional.