Drug & supplement interaction

Baikal Skullcap + Estradiol

Estradiol brand names: Estrace, Gynodiol, Vagifem, Estring, Vivelle, and others.

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

Estradiol falls into 3 drug categories that Baikal Skullcap can interact with; the most serious is rated moderate. Theoretically, Baikal skullcap may increase levels of drugs metabolized by CYP1A2 enzymes.

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

Baikal Skullcap and Estradiol

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

Why Are There 3 Interactions?

Baikal Skullcap interacts with whole categories of medication. Estradiol falls into 3 of those categories, so it can interact with Baikal Skullcap 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 Estradiol

Estradiol falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Baikal Skullcap interacts with.

Theoretically, Baikal skullcap may increase levels of drugs metabolized by CYP1A2 enzymes.
In vitro evidence suggests that constituents of Baikal skullcap inhibit the activity of CYP1A2. This effect has not been reported 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 idea behind this pairing. Your body uses an enzyme called CYP1A2 to help break down estradiol. In lab tests (not in actual people), compounds in Baikal skullcap appear to slow that enzyme down. If that happened in your body, estradiol could clear a little more slowly and build up, which might mean stronger estrogen effects like breast tenderness, bloating, nausea, headaches, or spotting.

I want to be straight with you though: this is theoretical, based only on test-tube work, and it hasn't been seen in humans. So it's worth a mention, not a panic. If you're using vaginal estradiol, very little reaches your bloodstream anyway. Still, loop in your pharmacist or doctor before adding the herb so they can keep an eye on things.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kim, B. R., Kim, D. H., Park, R., Kwon, K. B., Ryu, D. G., Kim, Y. C., Kim, N. Y., Jeong, S., Kang, B. K., and Kim, K. S. Effect of an extract of the root of Scutellaria baicalensis and its flavonoids on aflatoxin B1 oxidizing cytochrome P450 enzymes. Pl PubMed
  2. Li, T., Li, N., Guo, Q., Ji, H., Zhao, D., Xie, S., Li, X., Qiu, Z., Han, D., Chen, X., and You, Q. Inhibitory effects of wogonin on catalytic activity of cytochrome P450 enzyme in human liver microsomes. Eur J Drug Metab Pharmacokinet. 6-29-2011; PubMed
Moderate

ESTROGENS

2 of 3

Estradiol also falls under ESTROGENS.

Theoretically, concomitant use of large amounts of Baikal skullcap might interfere with hormone replacement therapy, due to competition for estrogen receptors.
In vitro evidence suggests that Baikal skullcap has estrogenic activity.
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 estradiol and Baikal skullcap. Estradiol works by attaching to estrogen receptors in your body. In lab dishes, compounds in Baikal skullcap (like baicalein and wogonin) seem to have mild estrogen-like activity, so the theory is they could compete with estradiol at those same receptors and slightly nudge how well your hormone therapy works.

I want to be honest about how soft this evidence is. This comes only from test-tube and lab studies, not from real people, so we genuinely don't know if it matters in everyday use. Occasional culinary or tea amounts are unlikely to be an issue, but concentrated supplement doses are the bigger question mark. If you're considering a Baikal skullcap supplement alongside your estradiol, just run it by your pharmacist or doctor first.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Zhang CZ, Wang SX, Zhang Y, et al. In vitro estrogenic activities of Chinese medicinal plants traditionally used for the management of menopausal symptoms. J Ethnopharmacol 2005;98:295-300. PubMed
Minor

P-GLYCOPROTEIN SUBSTRATES

3 of 3

Estradiol also falls under P-GLYCOPROTEIN SUBSTRATES.

Theoretically, Baikal skullcap might increase levels of drugs transported by P-glycoprotein.
In vitro and animal research suggests that baicalein, oroxylin A, and wogonin, constituents of Baikal skullcap, can inhibit P-glycoprotein. This effect has not been reported in humans.
Severity Minor 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 your estradiol. Some compounds in Baikal skullcap (like baicalein and wogonin) have, in lab and animal studies, slowed down a little cellular pump called P-glycoprotein. Estradiol can ride along on that pump, so in theory blocking it could let a bit more estradiol stay in your system. More estradiol on board could mean side effects like breast tenderness, bloating, nausea, headaches, or spotting.

The important part: this is theoretical only. It comes from test-tube and animal work and has never been shown in people, and it's rated a minor interaction. If you use vaginal estradiol, very little reaches your bloodstream anyway. Still, it's worth a quick mention to your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lee, Y., Yeo, H., Liu, S. H., Jiang, Z., Savizky, R. M., Austin, D. J., and Cheng, Y. C. Increased anti-P-glycoprotein activity of baicalein by alkylation on the A ring. J Med Chem 10-21-2004;47(22):5555-5566. PubMed
  2. Lee, E., Enomoto, R., Suzuki, C., Ohno, M., Ohashi, T., Miyauchi, A., Tanimoto, E., Maeda, K., Hirano, H., Yokoi, T., and Sugahara, C. Wogonin, a plant flavone, potentiates etoposide-induced apoptosis in cancer cells. Ann N Y Acad Sci 2007;1095:521-526. PubMed
  3. Go, W. J., Ryu, J. H., Qiang, F., and Han, H. K. Evaluation of the flavonoid oroxylin A as an inhibitor of P-glycoprotein-mediated cellular efflux. J Nat Prod 2009;72(9):1616-1619. PubMed
  4. Enomoto, R., Koshiba, C., Suzuki, C., and Lee, E. Wogonin potentiates the antitumor action of etoposide and ameliorates its adverse effects. Cancer Chemother.Pharmacol 2011;67(5):1063-1072. 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

Baikal Skullcap Also Interacts With Other Medications

Baikal Skullcap has 593 moderate, 352 minor known drug interactions in our database — the Estradiol one above is among them. If you take anything else, check it against the full list below.

Moderate 593 Minor 352 No known interaction 1,885 (incl. Estradiol)
Taking anything else?

Check Another of Your Medications Against Baikal Skullcap

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

Everything else you take

See Every Supplement That Interacts With Estradiol

This page covers Baikal Skullcap only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Estradiol page lists 213 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 · 172 moderate · 38 minor.

From our pharmacist’s overview on the Estradiol page

“Estradiol (Estrace, Vivelle, Vagifem, and other brands) is estrogen therapy, and its interaction list deserves careful reading, especially the three entries rated major. Grapefruit can push estradiol levels higher, St.”

Reviewed by 2 · Jul 18, 2026

Open the Estradiol interaction page

One more smart check

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

We hold 737 real supplement products containing Baikal Skullcap, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Baikal Skullcap. Your product may carry other ingredients that interact with Estradiol too, on top of Baikal Skullcap — 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 Baikal Skullcap and 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 Baikal Skullcap
Top 25%

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

29 days ago today
Medication Estradiol
Top 25%

#380 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 Baikal Skullcap

What is Baikal Skullcap?

Baikal Skullcap
  • Inflammation
  • Allergies
  • Anxiety and sleep
  • Immune support
  • Respiratory infections

Baikal skullcap is a traditional Chinese herb (Huang Qin) used for inflammation, allergies, and infections, with active compounds like baicalin and baicalein studied mostly in the lab. Human evidence remains limited, so it should not replace proven treatments. Talk to your pharmacist or doctor before using it, and avoid it in pregnancy and breastfeeding.

Read the full Baikal Skullcap monograph & all interactions
Keep checking

Other Drugs & Baikal Skullcap

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

0Major
593Moderate
352Minor
1,884No known interaction
593 Moderate 352 Minor 1,884 No interaction
Moderate

593 interactions

Showing 60 of 593 moderate interactions — see all 593 on the Baikal Skullcap page.

Minor

352 interactions

Showing 60 of 352 minor interactions — see all 352 on the Baikal Skullcap page.

No interaction 1,884 drugs checked — show the list

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

Showing the 60 most looked-up of 1,884 medications checked with no known interaction — see the full Baikal Skullcap list.

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

Can you take Baikal Skullcap with 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 Baikal Skullcap and Estradiol?
Estradiol belongs to more than one drug category, and Baikal Skullcap 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 Baikal Skullcap and 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 Estradiol and Baikal Skullcap?

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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.