Drug & supplement interaction

Soy + Desogestrel, Ethinyl Estradiol

Desogestrel, Ethinyl Estradiol brand names: Ortho-Cept 28, Ortho-Cept 21, Marvelon 21, Marvelon 28, Desogen, and others.

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

Desogestrel, Ethinyl Estradiol falls into 2 drug categories that Soy can interact with; the most serious is rated moderate. Theoretically, soy might competitively inhibit the effects of estrogen replacement therapy.

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

Soy and Desogestrel, Ethinyl Estradiol

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

Why Are There 2 Interactions?

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

Moderate

ESTROGENS

1 of 2

Why this applies to Desogestrel, Ethinyl Estradiol

Desogestrel, Ethinyl Estradiol falls under ESTROGENS — the group Soy interacts with.

Theoretically, soy might competitively inhibit the effects of estrogen replacement therapy.
Soy contains phytoestrogens and has been shown to have estrogenic activity in some patients. Although this has not been demonstrated in humans, theoretically, concomitant use of soy with estrogen replacement therapy might reduce the effects of the estrogen replacement therapy.
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

Here's the thing to know about your birth control pill (desogestrel with ethinyl estradiol): the soy connection here is mostly theoretical. Soy contains plant compounds called phytoestrogens that can weakly bump up against the same receptors your pill's estrogen works on. On paper, that could slightly compete with the estrogen part, but this has never actually been shown to weaken a contraceptive or cause problems in real people.

For most folks, eating tofu, edamame, or soy milk as food is not going to interfere with how well your pill works. Concentrated soy isoflavone supplements are a bigger unknown, so if you're considering one, it's worth a quick chat with your pharmacist or doctor first. Don't change how you take your pill on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Nisley N, Klepser T. Phytoestrogens for the prevention and treatment of osteoporosis. Alt Med Alert 1999 Dec;138-42.
Minor

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

2 of 2

Desogestrel, Ethinyl Estradiol also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Soy might modestly induce CYP2C9 enzymes. However, this effect does not seem to be clinically significant.
In vitro research suggests that an unhydrolyzed soy extract might induce CYP2C9. However, the significance of this interaction is likely minimal. In healthy females taking a specific extract of soy (Genistein Soy Complex, Source Naturals), blood levels of losartan, a CYP2C9 substrate, were not significantly affected.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

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

Good question about pairing soy with your Desogen / Ortho-Cept (desogestrel with ethinyl estradiol) birth control pill. The theory here is that soy could mildly speed up a liver enzyme called CYP2C9, which in turn might lower hormone levels a bit. In plain terms, if your hormone levels dipped, the worry would be slightly less reliable pregnancy prevention or some breakthrough spotting.

The reassuring part: this concern comes only from lab and test-tube studies, and when soy was actually tested in people, drug levels didn't meaningfully change. So enjoying soy foods like tofu, edamame, or soy milk is very unlikely to affect your pill. If you plan to take concentrated soy isoflavone supplements regularly, just give your pharmacist or doctor a quick heads-up first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wang G, Xiao CQ, Li Z, et al. Effect of soy extract administration on losartan pharmacokinetics in healthy female volunteers. Ann Pharmacother 2009;43:1045-9. 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

Soy Also Interacts With Other Medications

Soy has 9 major, 342 moderate, 259 minor known drug interactions in our database — the Desogestrel, Ethinyl Estradiol one above is among them. If you take anything else, check it against the full list below.

Major 9 Moderate 342 Minor 259 No known interaction 2,220 (incl. Desogestrel, Ethinyl Estradiol)
Taking anything else?

Check Another of Your Medications Against Soy

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

Everything else you take

See Every Supplement That Interacts With Desogestrel, Ethinyl Estradiol

This page covers Soy only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Desogestrel, Ethinyl Estradiol page lists 246 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 · 201 moderate · 39 minor.

From our pharmacist’s overview on the Desogestrel, Ethinyl Estradiol page

“St. John's Wort is the supplement I would flag first for anyone on desogestrel with ethinyl estradiol (Desogen, Ortho-Cept, Marvelon).”

Reviewed by 2 · Jul 18, 2026

Open the Desogestrel, Ethinyl Estradiol interaction page

One more smart check

Taking Soy as Part of a Dietary Supplement Product? Check It for Interactions

We hold 821 real supplement products containing Soy, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Soy. Your product may carry other ingredients that interact with Desogestrel, Ethinyl Estradiol too, on top of Soy — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Soy and Desogestrel, Ethinyl Estradiol 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 Soy
Top 25%

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

29 days ago today
Medication Desogestrel, Ethinyl Estradiol
Top 25%

#444 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 Soy

What is Soy?

  • Menopause symptoms (hot flashes)
  • Heart and cholesterol health
  • Bone health
  • Plant-based protein source
  • General nutrition

Soy is a nutritious bean that is a staple food and a popular source of plant protein and isoflavones. Eating soy foods as part of a balanced diet is generally considered safe for most people, and there is moderate evidence it may modestly help cholesterol and some menopause symptoms, though results vary. Talk with your pharmacist or doctor before using concentrated soy isoflavone supplements, especially if you have a history of hormone-sensitive conditions.

Read the full Soy monograph & all interactions
Keep checking

Other Drugs & Soy

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

9Major
342Moderate
259Minor
2,219No known interaction
9 Major 342 Moderate 259 Minor 2,219 No interaction
Major

9 interactions

Moderate

342 interactions

Showing 60 of 342 moderate interactions — see all 342 on the Soy page.

Minor

259 interactions

Showing 60 of 259 minor interactions — see all 259 on the Soy page.

No interaction 2,219 drugs checked — show the list

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

Showing the 60 most looked-up of 2,219 medications checked with no known interaction — see the full Soy list.

See the full Soy interactions page
See every supplement checked against Desogestrel, Ethinyl Estradiol, 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
Soy monograph › Uses, safety, and every drug interaction in one place Desogestrel, Ethinyl Estradiol supplement interactions › Every supplement checked against Desogestrel, Ethinyl Estradiol, 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 Soy and Desogestrel, Ethinyl Estradiol Together: Common Questions

Can you take Soy with Desogestrel, Ethinyl Estradiol?
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 Soy and Desogestrel, Ethinyl Estradiol?
Desogestrel, Ethinyl Estradiol belongs to more than one drug category, and Soy 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 Soy and Desogestrel, Ethinyl Estradiol 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

Still Have a Question About Desogestrel, Ethinyl Estradiol and Soy?

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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.