Gumweed + Lapatinib
Lapatinib brand name: Tykerb.
We found no known interaction between Gumweed and Lapatinib 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.
Gumweed and Lapatinib
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 Lapatinib and Gumweed 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.
Worth understanding: our licensed dataset holds no drug-interaction record for Gumweed at all — not against Lapatinib, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.
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.
Gumweed safety at a glance
Safety guidance is general; always confirm with your pharmacist or doctor for your situation.
See Every Supplement That Interacts With Lapatinib
This page covers Gumweed only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Lapatinib page lists 143 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 · 100 moderate · 40 minor.
From our pharmacist’s overview on the Lapatinib page
“Of the 143 supplements on file for lapatinib (Tykerb), nearly all press on the same point, the CYP3A4 enzyme that clears this HER2-targeted breast cancer drug. That deserves real caution, since lapatinib only works when its blood level stays in range.”
Reviewed by 2 · Jul 18, 2026
Taking Gumweed as Part of a Dietary Supplement Product? Check It for Interactions
We hold 18 real supplement products containing Gumweed, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Gumweed. Even though Gumweed itself has no known interaction with Lapatinib, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:
Where Gumweed and Lapatinib 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.
#885 of 1,452 supplements looked up here in the last 7 days
#1,543 of 2,830 medications looked up here in the last 7 days
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 Gumweed reference on this page ↓
- Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Gumweed and Lapatinib 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.
About Gumweed
What is Gumweed?
- Cough and bronchitis
- Asthma-related breathing problems
- Skin irritation from poison ivy or poison oak
- Minor wounds and rashes
- Upper respiratory congestion
Gumweed is a traditional North American plant used mostly for coughs, chest congestion, and skin irritation such as poison ivy rashes. Good-quality human studies are lacking, so its benefits are not well proven, and it should be used cautiously and avoided during pregnancy and breastfeeding.
Grindelia robusta · Asteraceae · Dried leaves and flowering tops · Tea, tincture, liquid extract, capsules, topical preparations
An interaction check asks whether these two react with each other — it does not ask whether Gumweed is a good idea for someone in your situation. Here is what our Gumweed record says about it on its own.
Gumweed: dosing
There is no well-established, standardized dose for gumweed. Traditional preparations include teas, tinctures, and liquid extracts, but the strength of commercial products varies widely.The safest approach is to follow the directions on the product label and not exceed the suggested amount.
From our Gumweed monograph — the full record covers uses, side effects and every documented interaction.
About Lapatinib
What Is Lapatinib Used For?
Brand name: Tykerb
Lapatinib tablets — sold under the brand name Tykerb — are used to treat advanced or metastatic breast cancer in patients whose tumors overexpress the HER2 protein. They are always used in combination with another medicine, not alone.
Tykerb is approved in combination with capecitabine for HER2-positive advanced or metastatic breast cancer in patients who have already received prior treatment including an anthracycline, a taxane, and trastuzumab, and whose disease has progressed on trastuzumab. Tykerb is also approved in combination with letrozole for postmenopausal women with hormone receptor-positive, HER2-positive metastatic breast cancer when hormonal therapy is appropriate.
Most-Reported Side Effects for Lapatinib
From FAERS, the FDA’s public side-effect reporting system (15,427 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.
Other Drugs & Gumweed
Browse every other medication we’ve checked against Gumweed — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
No interaction 2,829 drugs checked — show the list
We also checked Gumweed against these medications and found no known interaction in our sources. Open any page to confirm.
- Apixaban ›
- Levothyroxine ›
- Amlodipine ›
- Methylphenidate ›
- Warfarin ›
- Sertraline ›
- Testosterone ›
- Losartan Potassium ›
- Ivermectin ›
- Abemaciclib ›
- Aspirin ›
- Acetaminophen ›
- Metoprolol ›
- Rosuvastatin ›
- Rivaroxaban ›
- Escitalopram ›
- Clopidogrel ›
- Atorvastatin ›
- Tadalafil ›
- Docusate ›
- Tirzepatide ›
- Ibuprofen ›
- Methamphetamine ›
- Hydroxyurea ›
- Warfarin Sodium ›
- Valacyclovir ›
- Sumatriptan ›
- Semaglutide ›
- Prednisone ›
- Lisdexamfetamine ›
- Propranolol ›
- Metformin ›
- Amitriptyline ›
- Amoxicillin ›
- Lisinopril ›
- Isotretinoin ›
- Amlodipine Besylate ›
- Methotrexate ›
- Bendamustine ›
- Bupropion ›
- Amphetamine ›
- Doxycycline ›
- Fluoxetine ›
- Azithromycin ›
- Acyclovir ›
- Lamotrigine ›
- Pregabalin ›
- Dextroamphetamine ›
- Gabapentin ›
- Acetaminophen, Codeine ›
- Quetiapine ›
- Clonazepam ›
- Levothyroxine, Liothyronine ›
- Naproxen ›
- Omeprazole ›
- Letrozole ›
- Methylene Blue ›
- Duloxetine ›
- Buspirone ›
- Citalopram ›
Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Gumweed list.
Gumweed References
The 3 references that drive our Gumweed 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.
- Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
- McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
- Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
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.
Taking Gumweed and Lapatinib Together: Common Questions
Is it safe to take Gumweed with Lapatinib?
Do Gumweed and Lapatinib have any of the same side effects?
Does Lapatinib interact with any supplements?
Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
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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.