Drug & supplement interaction

Equol + Ethinyl estradiol, Levonogestrel

Ethinyl estradiol, Levonogestrel brand name: Lybrel.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Ethinyl estradiol, Levonogestrel falls into 2 drug categories that Equol can interact with; the most serious is rated moderate. Theoretically, equol might increase the levels and clinical effects of ethinyl estradiol found in contraceptive drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Equol and Ethinyl estradiol, Levonogestrel

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Equol interacts with whole categories of medication. Ethinyl estradiol, Levonogestrel falls into 2 of those categories, so it can interact with Equol in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CONTRACEPTIVE DRUGS

1 of 2

Why this applies to Ethinyl estradiol, Levonogestrel

Ethinyl estradiol, Levonogestrel falls under CONTRACEPTIVE DRUGS — the group Equol interacts with.

Theoretically, equol might increase the levels and clinical effects of ethinyl estradiol found in contraceptive drugs.
In vitro research shows that equol inhibits the binding of estradiol to serum proteins. Theoretically, this might increase the concentration of free, bioactive estradiol, thereby increasing the risk of adverse effects from ethinyl estradiol, including headaches, breast tenderness, dysmenorrhea, and weight gain.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Lybrel contains two hormones, ethinyl estradiol (an estrogen) and levonorgestrel (a progestin). Here's the idea behind this interaction: equol, a soy-derived compound that acts a bit like estrogen, may bump some of your ethinyl estradiol off the proteins that normally carry it in your blood. That could leave a little more free, active estrogen floating around than usual.

In practice, that might mean more of the typical estrogen-related side effects, things like headaches, breast tenderness, painful periods, or some water weight. Honestly though, this is based only on lab test-tube research, not real patients, so it's quite theoretical. I wouldn't lose sleep over it, but if you're thinking about an equol supplement, run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Martin ME, Haouriqui M, Pelissero C, et al. Interactions between phytoestrogens and human sex steroid binding protein. Life Sci 1996;58:429-36. PubMed
Moderate

ESTROGENS

2 of 2

Ethinyl estradiol, Levonogestrel also falls under ESTROGENS.

Theoretically, equol might increase the levels and clinical effects of estrogens.
In vitro research shows that equol inhibits the binding of estradiol to serum proteins. Theoretically, this might increase the concentration of free, bioactive estradiol, thereby increasing the risk of adverse effects from estrogen replacement therapy, including headaches, breast tenderness, and weight gain.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Lybrel is a daily birth control pill that combines two hormones: ethinyl estradiol (a form of estrogen) and levonorgestrel (a progestin). The concern with equol is fairly indirect. In lab dishes, equol seems to bump estrogen off the proteins that normally carry it around in your blood. The thinking is that this could leave a little more free, active estrogen floating around, which might slightly nudge up estrogen-type side effects like headaches, breast tenderness, bloating, or mild weight gain.

Here is the honest part: this is theoretical and based only on test-tube research, not on real people. It is unlikely to cause real trouble for most. Still, before adding an equol supplement, check with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Martin ME, Haouriqui M, Pelissero C, et al. Interactions between phytoestrogens and human sex steroid binding protein. Life Sci 1996;58:429-36. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Equol Also Interacts With Other Medications

Equol has 57 moderate, 75 minor known drug interactions in our database — the Ethinyl estradiol, Levonogestrel one above is among them. If you take anything else, check it against the full list below.

Moderate 57 Minor 75 No known interaction 2,698 (incl. Ethinyl estradiol, Levonogestrel)
Taking anything else?

Check Another of Your Medications Against Equol

Covers the 2,830 medications we’ve checked against Equol. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Ethinyl estradiol, Levonogestrel

This page covers Equol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ethinyl estradiol, Levonogestrel page lists 239 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Grapefruit (major), Siberian Cocklebur (major) and St. John's Wort (major).

By severity: 6 major · 195 moderate · 38 minor.

From our pharmacist’s overview on the Ethinyl estradiol, Levonogestrel page

“A daily birth control pill like Lybrel (ethinyl estradiol with levonorgestrel) only works when enough hormone stays in the bloodstream, and that is exactly what several supplements on this page can undermine. This list deserves genuine care, starting with the six major-rated entries.”

Reviewed by 2 · Jul 18, 2026

Open the Ethinyl estradiol, Levonogestrel interaction page

How much people look this up

Where Equol and Ethinyl estradiol, Levonogestrel Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Equol
Steady interest

#906 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Ethinyl estradiol, Levonogestrel
Top 10%

#148 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Equol

What is Equol?

  • Menopause symptoms (hot flashes)
  • Bone health support
  • Skin aging
  • Prostate health
  • General hormone balance

Equol is a compound made in the gut when some people break down soy isoflavones, and it is also sold as a supplement. Early research links it to possible benefits for menopause symptoms and bone or skin health, but the evidence is still limited and far from proven. Talk with your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Read the full Equol monograph & all interactions
Keep checking

Other Drugs & Equol

Browse every other medication we’ve checked against Equol — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
57Moderate
75Minor
2,697No known interaction
57 Moderate 75 Minor 2,697 No interaction
Moderate

57 interactions

Minor

75 interactions

Showing 60 of 75 minor interactions — see all 75 on the Equol page.

No interaction 2,697 drugs checked — show the list

We also checked Equol against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,697 medications checked with no known interaction — see the full Equol list.

See the full Equol interactions page
See every supplement checked against Ethinyl estradiol, Levonogestrel, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Equol monograph › Uses, safety, and every drug interaction in one place Ethinyl estradiol, Levonogestrel supplement interactions › Every supplement checked against Ethinyl estradiol, Levonogestrel, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Equol and Ethinyl estradiol, Levonogestrel Together: Common Questions

Can you take Equol with Ethinyl estradiol, Levonogestrel?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 2 interactions listed for Equol and Ethinyl estradiol, Levonogestrel?
Ethinyl estradiol, Levonogestrel belongs to more than one drug category, and Equol interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Equol and Ethinyl estradiol, Levonogestrel interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.