Drug & supplement interaction

Lobelia + Lapatinib

Lapatinib brand name: Tykerb.

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

We found no known interaction between Lobelia 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.

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Interaction report

Lobelia 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 Lobelia 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.

Lobelia safety at a glance

Lobelia overall Use caution Lobelia can be toxic and cause serious effects at higher doses, so caution is strongly advised.
Pregnancy Likely Unsafe When used orally due to its emetic effects. There is insufficient reliable information available about the safety of lobelia when used topically during pregnanc... Read the full pregnancy detail
Breastfeeding Likely Unsafe When used orally due to its emetic effects. There is insufficient reliable information available about the safety of lobelia when used topically during pregnanc... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

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

Why No Interaction Is Listed for Lapatinib

Interactions in our licensed database are recorded against drug classes, not just single drug names. Lapatinib is filed under 3 classifications — cytochrome p450 3a4 (cyp3a4) inhibitors, cytochrome p450 3a4 (cyp3a4) substrates, oral drugs. Lobelia has documented interactions with 1 drug class — the most serious being lithium (moderate) — and none of Lapatinib’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

Lobelia Does Interact With Other Medications

Lobelia has 1 moderate known drug interaction in our database — Lapatinib isn’t one of them. If you take anything else, check it against the full list below.

Moderate 1 No known interaction 2,829 (incl. Lapatinib)
Taking anything else?

Check Another of Your Medications Against Lobelia

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

What to actually watch for

No Interaction Found — But Data Suggests Lobelia and Lapatinib May Share Several of the Same Side Effects

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.

  • Diarrhea / Vomiting / Nausea reported in 27.1% of FDA reports for Lapatinib Additional detail

    Lobelia

    “Orally, lobelia can cause nausea, vomiting, diarrhea, coughing, dizziness, tremors, and throat irritation. These adverse effects have been reported with doses as low as 50 mg (4,16414). Lobelia leaf can cause toxicity when taken in doses of 600 mg or higher. Symptoms of lobelia toxicity include sweating, tachycardia, convulsions, hypothermia, hypotension, coma, and death (4,11).”

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

    3 sources cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
    2. 16414. Stead LF, Hughes JR. Lobeline for smoking cessation. Cochrane Database Syst Rev 2000;2:CD000124. PubMed
    3. 11. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.

    “Orally, lobelia can cause nausea, vomiting, diarrhea, and throat irritation (4,16414).”

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

    2 sources cited
    1. 4. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
    2. 16414. Stead LF, Hughes JR. Lobeline for smoking cessation. Cochrane Database Syst Rev 2000;2:CD000124. PubMed

    Lapatinib

    Listed in the ADVERSE REACTIONS section of the FDA label for Lapatinib, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Lobelia but not commonly for Lapatinib: sore throat, seizures, a fast or pounding heartbeat and low blood pressure.

Effects for Lapatinib come from the ADVERSE REACTIONS section of its FDA label; effects for Lobelia come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 15,427 voluntary FDA FAERS reports for Lapatinib that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Lobelia in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Unsafe

When used orally due to its emetic effects. There is insufficient reliable information available about the safety of lobelia when used topically during pregnancy and lactation.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Everything else you take

See Every Supplement That Interacts With Lapatinib

This page covers Lobelia 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

Open the Lapatinib interaction page

One more smart check

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

We hold 482 real supplement products containing Lobelia, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lobelia. Even though Lobelia 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:

How much people look this up

Where Lobelia 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.

Supplement Lobelia
Top 25%

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

29 days ago today
Medication Lapatinib
Steady interest

#1,589 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 Lobelia reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Lobelia 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.
Data structure & sourcing designed and verified by .
Supplement

About Lobelia

What is Lobelia?

  • Asthma and breathing problems
  • Cough and bronchitis
  • Smoking cessation aid
  • Muscle relaxation

Lobelia is a traditional herb once used for breathing problems and to help people quit smoking, but reliable evidence supporting these uses is lacking. It can be toxic in higher amounts, causing serious side effects, so it should be used with great caution and only under professional guidance.

Lobelia inflata · Campanulaceae · Dried aerial parts (leaves, stems, flowers, and seeds) · Capsules, tinctures, liquid extracts, teas, and dried herb

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

Lobelia: dosing

There is no well-established or standardized safe dose of lobelia. Because the plant can be toxic, the amount that helps and the amount that harms may be close together.If a product is used, follow the directions on the label carefully and do not exceed them. We do not recommend self-dosing this herb without professional guidance.

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

Read the full Lobelia monograph & all interactions
Medication

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.

Diarrhea 4,174 reports
Nausea 1,615 reports
Fatigue 1,305 reports
Vomiting 1,209 reports
Rash 1,061 reports
See full Lapatinib drug information
Keep checking

Other Drugs & Lobelia

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

0Major
1Moderate
0Minor
2,828No known interaction
1 Moderate 2,828 No interaction
Moderate

1 interaction

No interaction 2,828 drugs checked — show the list

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

Showing the 60 most looked-up of 2,828 medications checked with no known interaction — see the full Lobelia list.

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

Lobelia References

The 6 references that drive our Lobelia 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. Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
  2. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  3. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  4. McChargue DE, Collins FL Jr, Cohen LM. Effect of non-nicotinic moist snuff replacement and lobeline on withdrawal symptoms during 48-h smokeless tobacco deprivation. Nicotine Tob Res 2002;4:195-200. PubMed
  5. Stead LF, Hughes JR. Lobeline for smoking cessation. Cochrane Database Syst Rev 2000;2:CD000124. PubMed
  6. Plakun, A. L., Ambrus, J., Bross, I., Graham, S., Levin, M. L., and Ross, C. A. Clinical factors in smoking withdrawal: preliminary report. Am J Public Health Nations.Health 1966;56(3):434-441. 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 Lobelia and Lapatinib Together: Common Questions

Is it safe to take Lobelia with Lapatinib?
We do not list a known interaction between Lobelia and Lapatinib. 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 Lobelia and Lapatinib have any of the same side effects?
Yes — our sources link each of them separately to 3 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.
How was the Lobelia and Lapatinib combination checked?
Interactions in our licensed database are recorded against drug classes. Lapatinib is filed under 3 classifications, and Lobelia has documented interactions with 1 drug class — none of Lapatinib'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 Lobelia interact with any other medications?
Yes. Lobelia has 1 documented drug interaction in our database — Lapatinib 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 Lapatinib interact with any supplements?
Yes. Lapatinib has documented interactions with 143 supplements in our database — Lobelia is not one of them. The Lapatinib 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

Lobelia monograph Uses, safety profile, and every drug interaction in one place Lapatinib drug information The full plain-English guide to this medication Lapatinib supplement interactions Every supplement checked against Lapatinib, 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 Lapatinib and Lobelia?

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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.