Does Fluconazole Interact With Birth Control?

Answer

Diflucan (fluconazole) is safe to take with birth control pills (i.e. oral hormonal contraceptives) and Nexplanon, a contraceptive implant. It will not decrease the effectiveness of your birth control.

In fact, Diflucan may actually increase estrogen concentrations from certain birth control pills since it can inhibit how our body metabolizes the hormone. This can cause an increase in some minor side effects, like nausea and breast tenderness.

Interaction Details

Diflucan is a CYP3A4 inhibitor, which is a metabolizing enzyme responsible for the metabolism of both:

• Estradiol valerate
• Dienogest

Diflucan inhibition of CYP3A4 activity may, therefore, increase estrogen concentrations and estrogenic-related side effects (due to decreased metabolism), such as:

• Nausea
• Breast tenderness

The prescribing information for Natazia, a combination hormone birth control pill containing estradiol valerate and dienogest, cites a study that found ketoconazole, another CYP3A4 inhibitor, significantly increased maximum concentrations of both hormones. While this won't decrease efficacy, it may increase side effects.

There are also studies that have looked specifically at fluconazole with birth control. One 2001 study concluded the following:

"The concomitant administration of 300 mg fluconazole once weekly, twice the recommended dose for vaginal candidiasis, to women using OCs [oral contraceptives] results in a slight increase in OC concentrations. Therefore, it appears that there is no threat of contraceptive failure because of concomitant fluconazole administration."

The Prescribing Information for fluconazole contains several points on how it affects the hormones contained in oral contraceptives.

It references 3 studies in which Ethinyl estradiol and progestin concentrations were measured after giving a dose of fluconazole to an individual.

In the first study, fluconazole was given at a dose of 50mg per day for 10 days. Both the estrogen and progestin concentrations were increased on average by 6% and 17% respectively

In the second study, patients were given a 200mg dose of fluconazole.  Both the estrogen and progestin concentrations were raised on average by 38% and 25% respectively.

Lastly, in the third study, patients were given a once-weekly dose of 300mg of fluconazole. Both the estrogen and progestin concentrations were raised on average by 24% and 13% respectively.

Diflucan Isn't An Antibiotic

Potential interactions between birth control and certain antibiotics are well-documented. We have written several articles regarding which antibiotics could potentially interfere with birth control.

The issue with antibiotics is that they can alter our "normal bacterial flora" in the gastrointestinal tract, which is responsible for estrogen enterohepatic recirculation. Decreasing bacteria in the GI tract may lower hormone concentrations according to some studies.

Other antibiotics, such as rifampin, can increase the metabolism of estrogen, which could decrease effectiveness. This is why you should be cautious about taking birth control with rifamycin antibiotics.

Diflucan however, is not an antibiotic, but an antifungal. It is not associated with a decrease in birth control effectiveness.

You can feel safe using your birth control as normal if you have been prescribed Diflucan.

About Diflucan

Diflucan is an antifungal medication available in oral and parenteral dosage forms. It is similar to ketoconazole and clotrimazole, but has a broader spectrum of activity, longer duration of action and is better absorbed in most cases.

It is used to treat a variety of infections caused by Candida, such as yeast infections, as well as for cryptococcal meningitis.

Diflucan can be taken with or without food.