Drug & supplement interaction

Collard + Trastuzumab

Trastuzumab brand name: Herceptin.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Collard and Trastuzumab 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

Collard and Trastuzumab

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 Trastuzumab and Collard 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.

Collard safety at a glance

Collard overall Generally safe Collard is widely eaten as a food and is generally safe for most people.
Pregnancy Generally safe Normal food amounts are considered safe and nutritious during pregnancy.
Breastfeeding Generally safe Eating collard as a food is generally considered safe while breastfeeding.

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

Still wondering about combining Trastuzumab and Collard? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
Keep it in perspective

Collard Does Interact With Other Medications

Collard has 86 moderate known drug interactions in our database — Trastuzumab isn’t one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Trastuzumab)
Taking anything else?

Check Another of Your Medications Against Collard

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

What to actually watch for

What Trastuzumab’s Own FDA Label Lists

This is not an interaction — none of it involves Collard. These are the most notable effects listed in the ADVERSE REACTIONS section of Trastuzumab’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

  • Trouble swallowing Worth acting on
  • Low potassium Worth acting on
  • Heart failure Worth acting on
  • An irregular heartbeat Worth acting on
  • Low mood Worth acting on
  • A low platelet count Worth acting on
  • Kidney problems Worth acting on
  • Anemia Worth acting on
  • Raised blood pressure Worth acting on
  • Shortness of breath Worth acting on

Showing the 10 most notable of 43 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Trastuzumab. Read the label on DailyMed › Where a percentage is shown, it is the share of 86,493 voluntary FDA FAERS reports for Trastuzumab that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Collard’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Collard side to compare — that is a limit of the record, not a statement that Collard has no side effects.

Overlapping uses

What Trastuzumab Is Prescribed For, and What Collard Has Been Studied For

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

Trastuzumab is prescribed for: Trastuzumab injection is used in adults to treat certain cancers that overexpress the HER2 protein. For breast cancer, it is used as adjuvant (after-surgery) treatment for early-stage HER2-positive breast cancer, in combination with certain chemotherapy regimens, as well as for metastatic (spread) HER2-positive breast cancer — either with paclitaxel as a first-line treatment or as a single agent after prior chemotherapy. Ontruzant is also indicated in adults for treatment of HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma (a type of stomach or esophageal junction cancer), in combination with cisplatin and capecitabine or 5-fluorouracil, for patients who have not received prior treatment for metastatic disease. Patients must be selected based on FDA-approved HER2 testing before starting therapy.

Collard has been studied for:

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

    Collard for breast cancer

    Population research has found that higher intake of cruciferous vegetables, including broccoli, Brussels sprout, cabbage, cauliflower, collards, and kale, is associated with a slight increase in the risk of breast cancer in premenopausal women, while higher intake of cruciferous vegetables appears to be associated with a slight but statistically insignificant decrease in the risk of breast cancer in postmenopausal wo…

    1 source cited
    1. 26188. Gaudet MM, Britton JA, Kabat GC, et al. Fruits, vegetables, and micronutrients in relation to breast cancer modified by menopause and hormone receptor status. Cancer Epidemiol Biomarkers Prev 2004;13(9):1485-94. DOI

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 Trastuzumab on your own; if you are taking Collard for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

One more smart check

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

We hold 379 real supplement products containing Collard, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Collard. Even though Collard itself has no known interaction with Trastuzumab, 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 Collard and Trastuzumab 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 Collard
Top half

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

29 days ago today
Medication Trastuzumab
Steady interest

#1,608 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 Collard reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Collard and Trastuzumab records this page draws on were last updated June 22, 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 Collard

What is Collard?

  • General nutrition and vitamin source
  • Bone health
  • Heart health support
  • Digestive fiber
  • Antioxidant intake

Collard is a leafy green vegetable in the cabbage family that is rich in vitamins, minerals, and fiber, and is best thought of as a nutritious food rather than a medicine. Eating it as part of a balanced diet is healthy for most people, but there is little high-quality research on collard as a concentrated supplement. If you take blood thinners or have kidney concerns, talk with your pharmacist or doctor because of its vitamin K and oxalate content.

Brassica oleracea var. viridis · Brassicaceae · Leaves · Fresh or cooked leaves, frozen greens; occasionally powders or capsules

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

Collard: dosing

There is no established medicinal dose for collard. As a food, it can be enjoyed in normal serving sizes as part of a varied diet, just like other vegetables.If you choose a collard powder or capsule, there is no standardized dose, so follow the directions on the product label.

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

Read the full Collard monograph & all interactions
Medication

About Trastuzumab Injection

What Is Trastuzumab Injection Used For?

Brand name: Herceptin

Trastuzumab injection is used in adults to treat certain cancers that overexpress the HER2 protein. For breast cancer, it is used as adjuvant (after-surgery) treatment for early-stage HER2-positive breast cancer, in combination with certain chemotherapy regimens, as well as for metastatic (spread) HER2-positive breast cancer — either with paclitaxel as a first-line treatment or as a single agent after prior chemotherapy.

Ontruzant is also indicated in adults for treatment of HER2-overexpressing metastatic gastric or gastroesophageal junction adenocarcinoma (a type of stomach or esophageal junction cancer), in combination with cisplatin and capecitabine or 5-fluorouracil, for patients who have not received prior treatment for metastatic disease. Patients must be selected based on FDA-approved HER2 testing before starting therapy.

Most-Reported Side Effects for Trastuzumab

From FAERS, the FDA’s public side-effect reporting system (88,598 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 7,825 reports
Nausea 6,098 reports
Fatigue 5,551 reports
Alopecia 5,432 reports
Disease progression 4,960 reports
See full Trastuzumab Injection drug information
Keep checking

Other Drugs & Collard

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Collard page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Collard list.

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

Collard References

The 4 references that drive our Collard 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. Zhao H, Lin J, Grossman HB, et al. Dietary isothiocyanates, GSTM1, GSTT1, NAT2 polymorphisms and bladder cancer risk. Int J Cancer 2007;120:2208-13.
  2. Cohen, J. H., Kristal, A. R., and Stanford, J. L. Fruit and vegetable intakes and prostate cancer risk. J Natl.Cancer Inst. 1-5-2000;92(1):61-68. PubMed
  3. Gaudet MM, Britton JA, Kabat GC, et al. Fruits, vegetables, and micronutrients in relation to breast cancer modified by menopause and hormone receptor status. Cancer Epidemiol Biomarkers Prev 2004;13(9):1485-94. DOI
  4. Amssayef A, Eddouks M. Antihyperglycemic Effect of the Moroccan Collard Green (Brassica oleracea var. viridis) in Streptozotocin-Induced Diabetic Rats. Endocr Metab Immune Disord Drug Targets 2020. 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 Collard and Trastuzumab Together: Common Questions

Is it safe to take Collard with Trastuzumab?
We do not list a known interaction between Collard and Trastuzumab. 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.
Are Collard and Trastuzumab 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 Collard in each. That is a conversation for your prescriber, especially if Trastuzumab is being adjusted to a target.
Does Collard interact with any other medications?
Yes. Collard has 86 documented drug interactions in our database — Trastuzumab is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

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

Where next

Keep Exploring

Collard monograph Uses, safety profile, and every drug interaction in one place Trastuzumab Injection drug information The full plain-English guide to this medication Trastuzumab supplement interactions Every supplement checked against Trastuzumab, 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 4 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Trastuzumab and Collard?

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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.