Drug & supplement interaction

Codonopsis + Letrozole

Letrozole brand name: Femara.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Codonopsis and Letrozole in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Codonopsis and Letrozole

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Letrozole and Codonopsis in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Codonopsis safety at a glance

Codonopsis overall Use caution Generally considered well tolerated in traditional food-like amounts, but high-quality safety data are limited.
Pregnancy Avoid Not enough reliable safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid Safety while breastfeeding is unknown, so avoid it unless your doctor advises otherwise.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Letrozole and Codonopsis? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Letrozole

Interactions in our licensed database are recorded against drug classes, not just single drug names. Letrozole is filed under 4 classifications — including aromatase inhibitors, cytochrome p450 2c19 (cyp2c19) inhibitors, cytochrome p450 3a4 (cyp3a4) substrates. Codonopsis has documented interactions with 3 drug classes — the most serious being abiraterone (zytiga) (moderate), anticoagulant/antiplatelet drugs (moderate) and antidiabetes drugs (moderate) — and none of Letrozole’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Codonopsis Does Interact With Other Medications

Codonopsis has 211 moderate known drug interactions in our database — Letrozole isn’t one of them. If you take anything else, check it against the full list below.

Moderate 211 No known interaction 2,619 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Codonopsis

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

What to actually watch for

No Interaction Found — But Data Suggests Codonopsis and Letrozole May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Dizziness Additional detail

    Codonopsis

    “Orally, very large doses of codonopsis (30-60 grams) may cause vision problems, dizziness, loss of balance, leg spasms, and confusion (12).”

    Codonopsis · Natural Medicines adverse-effect record, reported in vertigo.

    1 source cited
    1. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.

    Letrozole

    Listed in the ADVERSE REACTIONS section of the FDA label for Letrozole. Read the label on DailyMed ›

Reported for Codonopsis but not commonly for Letrozole: an allergic reaction, unsteadiness, a severe allergic reaction and an irregular heartbeat.

Effects for Letrozole come from the ADVERSE REACTIONS section of its FDA label; effects for Codonopsis come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Letrozole Is Prescribed For, and What Codonopsis Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Letrozole is a prescription medicine with approved uses on its FDA label. Codonopsis is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Letrozole is prescribed for: Letrozole (brand name Femara) is used to treat breast cancer in postmenopausal women whose tumors are driven by estrogen. It is used in three settings: as adjuvant (after-surgery) treatment for hormone receptor positive early breast cancer; as extended adjuvant treatment for women who have already completed about five years of tamoxifen therapy; and as first- or second-line treatment for locally advanced or metastatic (spread) breast cancer. Femara is specifically indicated for first-line treatment of hormone receptor positive or receptor-unknown locally advanced or metastatic breast cancer, and for advanced breast cancer in women whose disease has progressed after antiestrogen therapy.

Codonopsis has been studied for:

  • Cancer studied, not established Codonopsis has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Codonopsis for cancer

    Although there is interest in using oral Codonopsis lanceolata for cancer, there is insufficient reliable information about the clinical effects of codonopsis for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Letrozole on your own; if you are taking Codonopsis for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Codonopsis or Letrozole

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Codonopsis or Letrozole, 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 Letrozole

This page covers Codonopsis only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Letrozole page lists 142 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), 7-methoxyflavone (moderate) and Acacia Rigidula (moderate).

By severity: 3 major · 99 moderate · 40 minor.

From our pharmacist’s overview on the Letrozole page

“Letrozole (Femara) is prescribed to keep hormone-driven breast cancer from returning, so a supplement that shifts its blood level can quietly undercut treatment. Give this list of 142 ingredients genuine respect, and learn the three major entries first.”

Reviewed by 2 · Jul 18, 2026

Open the Letrozole interaction page

One more smart check

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

We hold 493 real supplement products containing Codonopsis, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Codonopsis. Even though Codonopsis itself has no known interaction with Letrozole, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Codonopsis and Letrozole 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 Codonopsis
Top half

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

29 days ago today
Medication Letrozole
Top 5%

#51 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Codonopsis reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Codonopsis and Letrozole records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Codonopsis

What is Codonopsis?

  • Fatigue and low energy
  • Digestive support and poor appetite
  • Immune support
  • General tonic ('qi' tonic in Traditional Chinese Medicine)
  • Cough and weakness during recovery from illness

Codonopsis (often called 'dang shen') is a root long used in Traditional Chinese Medicine as a gentle energy and digestive tonic, frequently as a milder substitute for ginseng. Human research is very limited, so its benefits are not well proven. It appears reasonably well tolerated in food-like amounts, but you should talk with a pharmacist or doctor before using it, especially if you are pregnant, breastfeeding, or have a health condition.

Codonopsis pilosula · Campanulaceae · Dried root · Dried root, slices, decoctions (teas/soups), powders, capsules, tinctures, and herbal formulas

An interaction check asks whether these two react with each other — it does not ask whether Codonopsis is a good idea for someone in your situation. Here is what our Codonopsis record says about it on its own.

Codonopsis: dosing

There is no official, standardized dose of Codonopsis. Traditional preparations often use the dried root in soups or decoctions, while commercial products come as capsules, powders, and tinctures in widely varying strengths.Follow the directions on your specific product label, and do not assume more is better. A pharmacist or doctor can help you decide whether it is appropriate for you and what amount may be reasonable.

From our Codonopsis monograph — the full record covers uses, side effects and every documented interaction.

Read the full Codonopsis monograph & all interactions
Medication

About Letrozole

What Is Letrozole Used For?

Brand name: Femara

Letrozole (brand name Femara) is used to treat breast cancer in postmenopausal women whose tumors are driven by estrogen. It is used in three settings: as adjuvant (after-surgery) treatment for hormone receptor positive early breast cancer; as extended adjuvant treatment for women who have already completed about five years of tamoxifen therapy; and as first- or second-line treatment for locally advanced or metastatic (spread) breast cancer.

Femara is specifically indicated for first-line treatment of hormone receptor positive or receptor-unknown locally advanced or metastatic breast cancer, and for advanced breast cancer in women whose disease has progressed after antiestrogen therapy.

See full Letrozole drug information
Keep checking

Other Drugs & Codonopsis

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

0Major
211Moderate
0Minor
2,618No known interaction
211 Moderate 2,618 No interaction
Moderate

211 interactions

Showing 60 of 211 moderate interactions — see all 211 on the Codonopsis page.

No interaction 2,618 drugs checked — show the list

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

Showing the 60 most looked-up of 2,618 medications checked with no known interaction — see the full Codonopsis list.

See the full Codonopsis interactions page
See every supplement checked against Letrozole, ranked by severity
Evidence & sources

Codonopsis References

The 5 references that drive our Codonopsis monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  2. Xu, X., Wang, S. R., and Lin, Q. [Clinical and experimental study on codonopsis pilosula oral liquor in treating coronary heart disease with blood stasis]. Zhongguo Zhong.Xi.Yi.Jie.He.Za Zhi. 1995;15(7):398-400.
  3. Hur GY, Choi GS, Park HJ, Ye YM, Park HS. Anaphylactic shock induced by Codonopsis lanceolata, traditional Chinese medicine in a patient with allergic rhinitis. Allergy. 2008;63(10):1406-7.
  4. Zhang ZB, Ip SP, Cho WCS, et al. Herb-drug interactions between androgenic Chinese herbal medicines and androgen receptor antagonist on tumor growth: Studies on two xenograft prostate cancer animal models. Phytother Res. 2021.
  5. Jia W, Bi Q, Jiang S, et al. Hypoglycemic activity of Codonopsis pilosula (Franch.) Nannf. in vitro and in vivo and its chemical composition identification by UPLC-Triple-TOF-MS/MS. Food Funct 2022;13(5):2456-2464.

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Codonopsis and Letrozole Together: Common Questions

Is it safe to take Codonopsis with Letrozole?
We do not list a known interaction between Codonopsis and Letrozole. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Codonopsis and Letrozole have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Codonopsis and Letrozole used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Codonopsis in each. That is a conversation for your prescriber, especially if Letrozole is being adjusted to a target.
How was the Codonopsis and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Codonopsis has documented interactions with 3 drug classes — none of Letrozole's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Codonopsis interact with any other medications?
Yes. Codonopsis has 211 documented drug interactions in our database — Letrozole is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Letrozole interact with any supplements?
Yes. Letrozole has documented interactions with 142 supplements in our database — Codonopsis is not one of them. The Letrozole interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Codonopsis monograph Uses, safety profile, and every drug interaction in one place Letrozole drug information The full plain-English guide to this medication Letrozole supplement interactions Every supplement checked against Letrozole, 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 References The 5 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Codonopsis?

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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.