Drug & supplement interaction

Black Currant + 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 Black Currant 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.

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Interaction report

Black Currant 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 Black Currant 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.

Black Currant safety at a glance

Black Currant overall Use caution The berry is safe as a food, but concentrated supplements are less studied and should be used carefully.
Pregnancy Use caution Eating the berry in food amounts is likely fine, but supplements lack safety data, so check with your doctor first.
Breastfeeding Use caution Food amounts are probably okay, but there is not enough information on concentrated supplements, so use caution.

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

Still wondering about combining Letrozole and Black Currant? 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. Black Currant has documented interactions with 2 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate) and phenothiazines (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

Black Currant Does Interact With Other Medications

Black Currant has 140 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 140 No known interaction 2,690 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Black Currant

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

What to actually watch for

What Black Currant Itself Has Been Linked To

This is not an interaction — nothing below involves Letrozole. It is the side-effect record for Black Currant on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Black Currant, this list is the first place to look.

  • Diarrhea Additional detail

    “Of 2154 patients with hyperlipidemia taking black currant seed oil 1.8 grams twice daily for 6 weeks, 8 reports of mild diarrhea were considered related to the supplement. These adverse reactions were reported 2-10 days after beginning treatment with black currant seed oil.”

    Black Currant · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 17638. Fa-lin Z, Zhen-yu W, Yan H, et al. Efficacy of blackcurrant oil soft capsule, a Chinese herbal drug, in hyperlipidemia treatment. Phytother Res 2010;24 Suppl 2:S209-13. PubMed

Everything above comes from the Natural Medicines adverse-effect record for Black Currant — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Letrozole’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Letrozole column appears here.

From our Q&A

Questions About Black Currant 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 Black Currant 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 Black Currant 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 Black Currant as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,265 real supplement products containing Black Currant, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Currant. Even though Black Currant 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 Black Currant 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 Black Currant
Top 25%

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

29 days ago today
Medication Letrozole
Top 5%

#50 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 Black Currant reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Black Currant 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 Black Currant

What is Black Currant?

Black Currant
  • Dry eyes and eye strain
  • Joint pain and inflammation
  • Immune and general wellness support
  • Cardiovascular health
  • Skin conditions (such as dry skin or eczema)

Black currant is a nutritious berry that is rich in vitamin C and antioxidants, and its seed oil contains the omega-6 fatty acid GLA. While it is enjoyed safely as a food and is popular as a supplement, solid human evidence for most health claims is still limited. Talk with your pharmacist or doctor before using concentrated supplements, especially if you are pregnant, nursing, or have a medical condition.

Ribes nigrum · Grossulariaceae · Berries (fruit), seeds (seed oil), and leaves · Whole berries, juice, capsules, seed oil softgels, dried leaf for tea, extracts

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

Black Currant: dosing

There is no official standardized dose for black currant supplements. The right amount can vary depending on the form (berry, juice, seed oil, or leaf) and the product's strength.Because doses are not well established, the safest approach is to follow the directions on the product label and not exceed them.

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

Read the full Black Currant 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 & Black Currant

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

0Major
140Moderate
0Minor
2,689No known interaction
140 Moderate 2,689 No interaction
Moderate

140 interactions

Showing 60 of 140 moderate interactions — see all 140 on the Black Currant page.

No interaction 2,689 drugs checked — show the list

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

Showing the 60 most looked-up of 2,689 medications checked with no known interaction — see the full Black Currant list.

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

Black Currant References

The 6 references that drive our Black Currant 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. Guivernau M, Meza N, Barja P, Roman O. Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandins Leukot Essent Fatty A PubMed
  2. Fa-lin Z, Zhen-yu W, Yan H, et al. Efficacy of blackcurrant oil soft capsule, a Chinese herbal drug, in hyperlipidemia treatment. Phytother Res 2010;24 Suppl 2:S209-13. PubMed
  3. Holman CP and Bell AF. A trial of evening primrose oil in the treatment of chronic schizophrenia. J Orhtomolecular Psych 1983;12:302-304.
  4. Vaddadi KS. The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia. Prostaglandins Med 1981;6(4):375-379. PubMed
  5. Norred, C. L. and Brinker, F. Potential coagulation effects of preoperative complementary and alternative medicines. Alt Ther 2001;7(6):58-67.
  6. Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins Leukotrienes Essential Fatty Acids 2007;77:101-3. PubMed

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 Black Currant and Letrozole Together: Common Questions

Is it safe to take Black Currant with Letrozole?
We do not list a known interaction between Black Currant 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.
How was the Black Currant and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Black Currant has documented interactions with 2 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 Black Currant interact with any other medications?
Yes. Black Currant has 140 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 — Black Currant 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

Black Currant 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 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Black Currant?

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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.