Ethinyl Estradiol; Norethindrone with Griseofulvin Interaction Details
Brand Names Associated with Griseofulvin
- Fulvicin P/G®
- Fulvicin-U/F®
- Grifulvin V®
- Gris-PEG®
- Grisactin®
- Griseofulvin
- Ultragris®
Medical Content Editor Dr. Brian Staiger, PharmD
Last updated
Nov 12, 2023
Interaction Effect
Decreased contraceptive effectiveness
Interaction Summary
Griseofulvin may decrease the effectiveness of hormonal contraceptives and produce contraceptive failure, breakthrough bleeding, or irregular menstruation . The mechanism of action is thought to be an enhanced hepatic metabolism of contraceptive steroids by griseofulvin . Limited data suggest that the effects of this interaction may be more prevalent with combination contraceptives that contain a lower dose of estrogen . If coadministration is required, use an alternative method of contraception during coadministration and for at least 28 days after discontinuation griseofulvin .
Severity
Major
Onset
Delayed
Evidence
Established
How To Manage Interaction
Griseofulvin may decrease the effectiveness of hormonal contraceptives and produce contraceptive failure, breakthrough bleeding, or irregular menstruation . If coadministration is required, use an alternative method of contraception during coadministration and for at least 28 days after discontinuation of griseofulvin .
Mechanism Of Interaction
Increased metabolism of contraceptive steroids
Literature Reports
A) A case report described pregnancy occurring in a 25-year-old woman receiving griseofulvin and oral contraceptives concurrently. The woman, who had been taking the oral contraceptive (OC), Triphasil(R), for 4 years with no menstrual irregularities, was treated with ultramicrocrystalline griseofulvin 330 mg twice daily while continuing to use oral contraception. Two month after initiation of griseofulvin, her nails were greatly improved but she reported transient headaches. Two months later, the patient was found to be pregnant. Her last menstrual period had occurred 2 months after initiation of griseofulvin. The patient claimed to have taken her OC regularly and did not take any other medications during this period. It was postulated the pregnancy probably resulted from failure of the oral contraceptive due to an interaction between the oral contraceptive and griseofulvin .
B) A case report described oligomenorrhea and irregular menses in a 32-year-old woman receiving concomitant griseofulvin and oral contraceptive therapy with norethindrone 0.5 and 1 mg plus ethinyl estradiol 0.035 mg (Ortho Novum 7/7/7(R)). The woman, who had two normal pregnancies and subsequent deliveries from 1981 to 1984 and who had been taking the oral contraceptive for the preceding four months with no abnormalities in menstruation, was diagnosed with tinea unguium. She was treated with griseofulvin 250 mg daily for 14 days, then increased to 500 mg daily for the remainder of the 6-month regimen. No other drugs were given. Following griseofulvin therapy initiation, the woman presented with oligomenorrhea and irregular menses. As a result, the patient's gynecologist changed her oral contraceptive to norgestrel 0.5 mg plus ethinyl estradiol 0.05 mg (Ovral-28(R)), providing a 57% increase in the estrogen component. Six months following the oral contraceptive change, the patient reported regular menses with normal menstrual flow .
C) The Safety of Medicines in the United Kingdom committee and the Netherlands Centre for Monitoring of Adverse Reactions to Drugs received 22 reports of a possible oral contraceptive (OC) and griseofulvin interaction. Among the 22 women using long-term OC who began receiving griseofulvin 0.5 to 1 g/day, 15 women (mean age, 26 years; range, 17 to 42 years; mean griseofulvin dose, 550 mg/day) reported transient intermenstrual bleeding and 5 women (mean age, 33.4 years; range, 17 to 44 years; mean griseofulvin dose, 880 mg/day) reported amenorrhea in the first and second cycles following griseofulvin initiation. In 7 of the intermenstrual bleeding cases and one of the amenorrhea cases, the women were using OCs with less than 50 mcg estrogen. Of the 20 women reporting menstrual irregularities, 14 women received no other drugs during the time of griseofulvin treatment and 3 women used drugs not known to interfere with OCs (ie, miconazole ointment, grass pollen vaccine, tetanus vaccine). In the 3 remaining patients, details of concurrent drug administration were not reported. In 2 patients with intermenstrual bleeding and 2 with amenorrhea, the original reaction recurred upon rechallenge with griseofulvin. Two unintended pregnancies were also reported among the 22 cases. In one case, the patient had been using a high-dose OC for 15 months and griseofulvin 500 mg/day for 2.5 months. One month after starting griseofulvin, she received a 1-week course of cotrimoxazole and became pregnant in that time period. In the second case, conception occurred when a patient was taking an unspecified OC, griseofulvin, and a combination of sulfonamides .
Griseofulvin Overview
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Griseofulvin is used to treat skin infections such as jock itch, athlete's foot, and ringworm; and fungal infections of the scalp, fingernails, and toenails.
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This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.
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Definitions
Severity Categories
Contraindicated
These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.
Major
This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.
Moderate
This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.
Minor
While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.
Onset
Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.
Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.
Evidence
Level of documentation of the interaction.
Established: The interaction is documented and substantiated in peer-reviewed medical literature.
Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.
How To Manage The Interaction
Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.
It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.
Mechanism Of Interaction
The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.
Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.
Where Does Our Information Come From?
Information for our drug interactions is compiled from several drug compendia, including:
The prescribing information for each drug, as published on DailyMED, is also used.
Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.
The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.