Short answer: Not in a way the label expects to cause pregnancy, but it can cause spotting. In a study, Qsymia 15 mg/92 mg lowered exposure to the estrogen in a combined pill by 16% and raised the progestin by 22%. The label says to keep taking the pill if spotting happens and tell the provider. Because topiramate can harm a fetus, it asks for effective contraception and monthly pregnancy tests.
The label describes a study in healthy volunteers with obesity (section 7). Repeated daily Qsymia 15 mg/92 mg was given with a single dose of a combined pill containing ethinyl estradiol 35 mcg and norethindrone 1 mg.
| Hormone | Change in exposure |
|---|---|
| Ethinyl estradiol (estrogen) | Down 16% |
| Norethindrone (progestin) | Up 22% |
The label says this interaction is not expected to raise the risk of pregnancy. It reports the study at the 15 mg/92 mg dose only and gives no figures for lower doses or for other pill brands.
The label explains that more progestin and less estrogen, which helps keep the uterine lining stable, can make irregular bleeding or spotting more common. Its advice is not to stop the combined pill if spotting occurs, and to tell the provider if the spotting is troubling (sections 7, 8.3).
The label gives this guidance for combined oral pills. It does not report studies with patches, rings, injections or intrauterine devices.
Qsymia is contraindicated in pregnancy (sections 4, 8.1). The label says it can cause fetal harm and that weight loss offers no clear benefit during pregnancy. Registry and population data show a higher risk of major birth defects, including cleft lip and cleft palate, and of babies small for their age after topiramate exposure in the womb. The label sets out these steps for people who can become pregnant:
The warning runs the other way on some injectable weight-loss medicines. The Zepbound label advises people on oral hormonal birth control to switch to a non-oral method, or add a barrier method, for 4 weeks after starting and for 4 weeks after each dose increase. It says non-oral hormonal methods should not be affected. See tirzepatide and the birth control pill.
People switching between weight-loss medicines can ask the prescriber which contraception advice applies to each. Dose Track can hold the start and dose-change dates that both labels count from.
Read more on Dose Track: Qsymia side effects · REMS · Phentermine-topiramate · Tirzepatide and the pill