Drug & supplement interaction

Thunder God Vine + Levonorgestrel

Levonorgestrel brand names: Plan B, Mirena, Levonelle One Step, Levonelle 1500, Norgeston, and others.

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

Thunder God Vine has a moderate interaction with Levonorgestrel. Theoretically, thunder god vine might increase the levels and clinical effects of CYP3A4 substrates.

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

Thunder God Vine and Levonorgestrel

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

Why this applies to Levonorgestrel

Levonorgestrel falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES — the group Thunder God Vine interacts with.

Theoretically, thunder god vine might increase the levels and clinical effects of CYP3A4 substrates.
In vitro research shows that triptolide, a constituent of thunder god vine, inhibits CYP3A4 enzymes in human microsomes. This interaction 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 basic idea. Levonorgestrel (think Plan B or your Mirena IUD) is partly broken down by a liver enzyme called CYP3A4. Lab studies suggest one of the compounds in Thunder God Vine, triptolide, can slow that enzyme down. In theory, that could let a bit more levonorgestrel hang around in your body, which might mean more of its usual side effects like spotting, breast tenderness, nausea, or headache.

I want to be honest about how soft this is. This concern comes only from test-tube research, not real people, so we truly don't know if it matters in practice. Levonorgestrel isn't a prodrug, so it doesn't need this enzyme to work. Since Thunder God Vine itself can be risky, please loop in your doctor or pharmacist before combining the two.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Song W, Liu M, Wu J, Zhai H, Chen Y, Peng Z. Preclinical Pharmacokinetics of Triptolide: A Potential Antitumor Drug. Curr Drug Metab. 2019;20(2):147-154. 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

Thunder God Vine Also Interacts With Other Medications

Thunder God Vine has 848 moderate known drug interactions in our database — the Levonorgestrel one above is one of them. If you take anything else, check it against the full list below.

Moderate 848 No known interaction 1,982 (incl. Levonorgestrel)
Taking anything else?

Check Another of Your Medications Against Thunder God Vine

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

From our Q&A

Questions About Thunder God Vine or Levonorgestrel

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Thunder God Vine or Levonorgestrel, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Levonorgestrel

This page covers Thunder God Vine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levonorgestrel page lists 191 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 · 142 moderate · 43 minor.

From our pharmacist’s overview on the Levonorgestrel page

“St. John's wort tops my worry list for anyone using levonorgestrel (Plan B, Mirena, and other birth control).”

Reviewed by 2 · Jul 18, 2026

Open the Levonorgestrel interaction page

How much people look this up

Where Thunder God Vine and Levonorgestrel 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 Thunder God Vine
Steady interest

#1,029 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Levonorgestrel
Top 25%

#405 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 Thunder God Vine

What is Thunder God Vine?

Thunder God Vine
  • Rheumatoid arthritis
  • Lupus and autoimmune conditions
  • Inflammation
  • Skin conditions like psoriasis
  • Immune-related disorders

Thunder God Vine is a Chinese herb studied mainly for rheumatoid arthritis and other autoimmune conditions, with some promising but limited evidence. It can be toxic if prepared or dosed improperly, and may cause serious side effects, so it should only be used under medical supervision. Avoid it during pregnancy and breastfeeding.

Read the full Thunder God Vine monograph & all interactions
Medication

About Levonorgestrel

What Is Levonorgestrel Used For?

Brand names: Plan B, Mirena, Levonelle One Step, Levonelle 1500, Norgeston, Skyla, Liletta, Kyleena

Levonorgestrel is used in two very different ways depending on the product. As an intrauterine system (IUS), Mirena and Liletta prevent pregnancy for up to 8 years and also treat heavy menstrual bleeding for up to 5 years in people who choose intrauterine contraception. Kyleena prevents pregnancy for up to 5 years, and Skyla prevents pregnancy for up to 3 years — neither Kyleena nor Skyla is indicated for heavy menstrual bleeding.

As an oral tablet, products such as AfterPill, AfterPlan, Amazon Basic Care Levonorgestrel, Econ Morning After, Emergency Contraceptive, and Empowered Choice are used as emergency (backup) contraception to reduce the chance of pregnancy after unprotected sex or contraceptive failure. The oral tablet is not intended for routine birth control.

See full Levonorgestrel drug information
Keep checking

Other Drugs & Thunder God Vine

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

0Major
848Moderate
0Minor
1,981No known interaction
848 Moderate 1,981 No interaction
Moderate

848 interactions

Showing 60 of 848 moderate interactions — see all 848 on the Thunder God Vine page.

No interaction 1,981 drugs checked — show the list

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

Showing the 60 most looked-up of 1,981 medications checked with no known interaction — see the full Thunder God Vine list.

See the full Thunder God Vine interactions page
See every supplement checked against Levonorgestrel, 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
Thunder God Vine monograph › Uses, safety, and every drug interaction in one place Levonorgestrel supplement interactions › Every supplement checked against Levonorgestrel, ranked by severity Levonorgestrel drug information › The full plain-English guide to this medication 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 Thunder God Vine and Levonorgestrel Together: Common Questions

Can you take Thunder God Vine with Levonorgestrel?
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.
How serious is the Thunder God Vine and Levonorgestrel 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 Levonorgestrel and Thunder God Vine?

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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.