Drug & supplement interaction

Bulbine Natalensis + Ethinyl Estradiol

Ethinyl Estradiol brand name: Estinyl.

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

Ethinyl Estradiol falls into 3 drug categories that Bulbine Natalensis can interact with; the most serious is rated moderate. Theoretically, Bulbine natalensis stem might reduce the levels and clinical effects of CYP1A2 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Bulbine Natalensis and Ethinyl Estradiol

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Bulbine Natalensis interacts with whole categories of medication. Ethinyl Estradiol falls into 3 of those categories, so it can interact with Bulbine Natalensis in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

1 of 3

Why this applies to Ethinyl Estradiol

Ethinyl Estradiol falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Bulbine Natalensis interacts with.

Theoretically, Bulbine natalensis stem might reduce the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that Bulbine natalensis stem extract slightly induces CYP1A2 mRNA expression and enzyme activity. Theoretically, this may increase the metabolism of CYP1A2 substrates; however, this has not been studied in humans.
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 gist for ethinyl estradiol, which is the estrogen in many birth control pills and some hormone therapies. Your body clears it partly through a liver enzyme called CYP1A2. Lab studies suggest Bulbine natalensis may slightly speed up that enzyme, which in theory could break ethinyl estradiol down a little faster and lower its levels in your blood.

If that happened with a contraceptive pill, the worry would be weaker protection and possible breakeded through bleeding or spotting. But I want to be honest: this is only a theoretical, test-tube finding with no human studies, so we really don't know if it matters in real life. Given that and Bulbine's possible liver concerns, please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Husain I, Manda V, Alhusban M, et al. Modulation of CYP3A4 and CYP2C9 activity by Bulbine natalensis and its constituents: An assessment of HDI risk of B. natalensis containing supplements. Phytomedicine 2021;81:153416. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

2 of 3

Ethinyl Estradiol also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, Bulbine natalensis stem might reduce the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that Bulbine natalensis stem extract induces CYP3A4 mRNA expression and enzyme activity. Theoretically, this may increase the metabolism of CYP3A4 substrates, but this has not been studied in humans.
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 gist for ethinyl estradiol, the estrogen found in many birth control pills and in Estinyl. Your liver clears this estrogen partly through an enzyme called CYP3A4. Lab and test-tube research suggests Bulbine natalensis may speed that enzyme up (induce it). In theory, a faster enzyme could break down the estrogen more quickly, leaving less of it in your system.

What that could mean in plain terms: a weaker effect. If you rely on this for contraception, lower levels could mean breakthrough bleeding, spotting, or less reliable pregnancy protection. I want to be honest though, this is only a theoretical concern from animal and lab data, not human studies. Still, given the stakes with birth control, please check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Husain I, Dale OR, Manda V, et al. Bulbine natalensis (currently Bulbine latifolia) and select bulbine knipholones modulate the activity of AhR, CYP1A2, CYP2B6, and P-gp. Planta Med 2022;88(12):975-984. PubMed
Moderate

P-GLYCOPROTEIN SUBSTRATES

3 of 3

Ethinyl Estradiol also falls under P-GLYCOPROTEIN SUBSTRATES.

Theoretically, Bulbine natalensis stem might increase the levels and clinical effects of p-glycoprotein substrates.
In vitro research shows that Bulbine natalensis stem extract induces p-glycoprotein mRNA expression; however, effects on transporter expression were not evaluated.
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 honest picture: ethinyl estradiol (the estrogen in many birth control pills and in Estinyl) is moved around the body partly by a transporter called p-glycoprotein. Lab research suggests Bulbine natalensis may nudge that transporter's activity, which could in theory shift how much estrogen stays in your system. But this comes only from test-tube and animal work, not from people, so any real-world effect is uncertain and may be small.

If anything changed, you might notice typical estrogen-related effects like nausea, breast tenderness, headaches, or spotting. There's also a separate worry: animal studies hint this supplement may stress the liver, which is the same organ that handles estrogen. Please don't start or stop anything on your own. Just run it past your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Husain I, Manda V, Alhusban M, et al. Modulation of CYP3A4 and CYP2C9 activity by Bulbine natalensis and its constituents: An assessment of HDI risk of B. natalensis containing supplements. Phytomedicine 2021;81:153416. 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

Bulbine Natalensis Also Interacts With Other Medications

Bulbine Natalensis has 918 moderate known drug interactions in our database — the Ethinyl Estradiol one above is among them. If you take anything else, check it against the full list below.

Moderate 918 No known interaction 1,912 (incl. Ethinyl Estradiol)
Taking anything else?

Check Another of Your Medications Against Bulbine Natalensis

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

Everything else you take

See Every Supplement That Interacts With Ethinyl Estradiol

This page covers Bulbine Natalensis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ethinyl Estradiol page lists 211 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 170 moderate · 38 minor.

From our pharmacist’s overview on the Ethinyl Estradiol page

“Ethinyl estradiol (Estinyl) is the estrogen in many birth control pills, and I treat its supplement list with real care, because the stake is not just side effects but whether the pill keeps working. Three of its 211 interacting ingredients are rated major, and those come first: St.”

Reviewed by 2 · Jul 18, 2026

Open the Ethinyl Estradiol interaction page

One more smart check

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

We hold 51 real supplement products containing Bulbine Natalensis, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Bulbine Natalensis. Your product may carry other ingredients that interact with Ethinyl Estradiol too, on top of Bulbine Natalensis — 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 Bulbine Natalensis and 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 Bulbine Natalensis
Steady interest

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

29 days ago today
Medication Ethinyl Estradiol
Steady interest

#2,029 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 Bulbine Natalensis

What is Bulbine Natalensis?

  • Boosting testosterone
  • Improving libido
  • Muscle building and athletic performance
  • General male vitality

Bulbine natalensis is a South African plant marketed mainly as a testosterone-boosting and libido supplement, but the human evidence is essentially absent and most claims come from animal studies. Animal research has also raised concerns about possible liver and kidney harm at higher doses, so caution is warranted. Talk to your pharmacist or doctor before trying it.

Read the full Bulbine Natalensis monograph & all interactions
Keep checking

Other Drugs & Bulbine Natalensis

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

0Major
918Moderate
0Minor
1,911No known interaction
918 Moderate 1,911 No interaction
Moderate

918 interactions

Showing 60 of 918 moderate interactions — see all 918 on the Bulbine Natalensis page.

No interaction 1,911 drugs checked — show the list

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

Showing the 60 most looked-up of 1,911 medications checked with no known interaction — see the full Bulbine Natalensis list.

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

Can you take Bulbine Natalensis with 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 3 interactions listed for Bulbine Natalensis and Ethinyl Estradiol?
Ethinyl Estradiol belongs to more than one drug category, and Bulbine Natalensis 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 Bulbine Natalensis and 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

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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.