Drug & supplement interaction

Lobelia + Ketoconazole

Ketoconazole brand name: Nizoral.

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 Ketoconazole 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 Ketoconazole

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 Ketoconazole 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 Ketoconazole and Lobelia? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Ketoconazole

Interactions in our licensed database are recorded against drug classes, not just single drug names. Ketoconazole is filed under 8 classifications — including antifungals, cytochrome p450 2c19 (cyp2c19) inhibitors, cytochrome p450 2c9 (cyp2c9) inhibitors. Lobelia has documented interactions with 1 drug class — the most serious being lithium (moderate) — and none of Ketoconazole’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 — Ketoconazole 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. Ketoconazole)
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 Ketoconazole 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.

  • Dizziness 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 dizziness and tremors. High doses of lobelia leaf can cause toxicity. Symptoms of lobelia toxicity include convulsions, coma, and death (4,11).”

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

    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. 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.

    Ketoconazole

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

  • Diarrhea / Vomiting / Nausea Additional detail

    Lobelia

    “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

    Ketoconazole

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

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

Effects for Ketoconazole come from the ADVERSE REACTIONS section of its FDA label; effects for Lobelia 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.

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

From our Q&A

Questions About Lobelia or Ketoconazole

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

This page covers Lobelia only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ketoconazole page lists 182 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Grapefruit (major), Siberian Cocklebur (major) and St. John's Wort (major).

By severity: 6 major · 135 moderate · 41 minor.

From our pharmacist’s overview on the Ketoconazole page

“Ketoconazole (Nizoral) is already hard on the liver, so treat its 182 interacting supplements with genuine care, starting with the six rated major. Most of the list runs through CYP3A4, the liver enzyme ketoconazole strongly blocks, so it can raise levels of over a hundred herbal ingredients, while grapefruit pushes ketoconazole itself…”

Reviewed by 2 · Jul 18, 2026

Open the Ketoconazole 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 Ketoconazole, 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 Ketoconazole 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 Ketoconazole
Steady interest

#2,081 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 Ketoconazole 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 Ketoconazole

What Is Ketoconazole Used For?

Brand name: Nizoral

Ketoconazole 2% shampoo and foam are used to treat tinea versicolor (also called pityriasis versicolor) — a fungal infection caused by Pityrosporum orbiculare (also known as Malassezia furfur), a yeast that naturally lives on the skin.

This infection creates light or dark patches, most often on the trunk, neck, arms, and upper thighs. Even after the fungus is cleared, those skin patches may take months to return to their normal color — that's normal, and depends on your skin type and sun exposure. Tinea versicolor can also come back, since the fungus lives on healthy skin even when there's no active infection.

Most-Reported Side Effects for Ketoconazole

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Pruritus 984 reports
Fatigue 975 reports
Nausea 873 reports
Rash 858 reports
Diarrhea 814 reports
See full Ketoconazole 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 Ketoconazole, 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 Ketoconazole Together: Common Questions

Is it safe to take Lobelia with Ketoconazole?
We do not list a known interaction between Lobelia and Ketoconazole. 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 Ketoconazole have any of the same side effects?
Yes — our sources link each of them separately to 4 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 Ketoconazole combination checked?
Interactions in our licensed database are recorded against drug classes. Ketoconazole is filed under 8 classifications, and Lobelia has documented interactions with 1 drug class — none of Ketoconazole'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 — Ketoconazole 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 Ketoconazole interact with any supplements?
Yes. Ketoconazole has documented interactions with 182 supplements in our database — Lobelia is not one of them. The Ketoconazole 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 Ketoconazole drug information The full plain-English guide to this medication Ketoconazole supplement interactions Every supplement checked against Ketoconazole, 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 Ketoconazole and Lobelia?

Our pharmacists answer your medication & supplement questions — free.

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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.