Drug & supplement interaction

Usnea + Erlotinib

Erlotinib brand name: Tarceva.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 27, 2026
The bottom line No known interaction

We found no known interaction between Usnea and Erlotinib 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 label for Erlotinib states a food rule worth keeping to, and 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

Usnea and Erlotinib

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 Erlotinib and Usnea 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 Usnea at all — not against Erlotinib, 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.

Usnea safety at a glance

Usnea overall Use caution Topical use is generally better tolerated, but oral usnic acid has been linked to liver damage.
Pregnancy Avoid Not enough safety data; avoid use during pregnancy.
Breastfeeding Avoid Not enough safety data; avoid use while breastfeeding.

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

Still wondering about combining Erlotinib and Usnea? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Usnea and Erlotinib 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. One of them is worth acting on rather than waiting out — marked below.

  • Liver problems Worth acting on Additional detail

    Usnea

    “Orally, usnic acid, a constituent of usnea, has been associated with reports of hepatotoxicity. From July to December 2000 there were at least seven cases of acute hepatotoxicity in patients taking LipoKinetix, a product containing usnic acid as sodium usniate.”

    Usnea · Natural Medicines adverse-effect record, reported in fatigue.

    6 sources cited
    1. 7091. Favreau JT, Ryu Ml, Braunstein G, et al. Severe hepatotoxicity associated with the dietary supplement LipoKinetix. Ann Intern Med 2002;136:590-5. PubMed
    2. 81595. Durazo, F. A., Lassman, C., Han, S. H., Saab, S., Lee, N. P., Kawano, M., Saggi, B., Gordon, S., Farmer, D. G., Yersiz, H., Goldstein, R. L., Ghobrial, M., and Busuttil, R. W. Fulminant liver failure due to usnic acid for weight loss. Am.J Gastroenterol. PubMed
    3. 81600. Neff, G. W., Reddy, K. R., Durazo, F. A., Meyer, D., Marrero, R., and Kaplowitz, N. Severe hepatotoxicity associated with the use of weight loss diet supplements containing ma huang or usnic acid. J Hepatol. 2004;41(6):1062-1064. PubMed
    4. 81607. Hsu, L. M., Huang, Y. S., Chang, F. Y., and Lee, S. D. 'Fat burner' herb, usnic Acid, induced acute hepatitis in a family. J Gastroenterol.Hepatol. 2005;20(7):1138-1139. PubMed
    5. 81612. Arneborn, P., Jansson, A., and Bottiger, Y. [Acute hepatitis in a woman after intake of slimming pills bought via Internet]. Lakartidningen 7-11-2005;102(28-29):2071-2072.
    6. 81619. Sanchez, W., Maple, J. T., Burgart, L. J., and Kamath, P. S. Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc 2006;81(4):541-544. PubMed

    Erlotinib

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

  • Weight loss / Tiredness / Nausea reported in 5.8% of FDA reports for Erlotinib Additional detail

    Usnea

    Recorded for Usnea in the same Natural Medicines adverse-effect record shown under Liver problems above.

    Erlotinib

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

  • A skin rash reported in 10.6% of FDA reports for Erlotinib Additional detail

    Usnea

    “Topically, usnea and its constituent, usnic acid, can cause allergic contact dermatitis with respiratory symptoms.”

    Usnea · Natural Medicines adverse-effect record, reported in dermatitis.

    3 sources cited
    1. 11720. Ingolfsdottir K. Usnic acid. Phytochemistry 2002;61:729-36.
    2. 81580. Mitchell, J. C. Allergy to lichens. Allergic contact dermatitis from usnic acid produced by lichenized fungi. Arch Dermatol 1965;92(2):142-146.
    3. 81632. Rafanelli, S., Bacchilega, R., Stanganelli, I., and Rafanelli, A. Contact dermatitis from usnic acid in vaginal ovules. Contact Dermatitis 1995;33(4):271-272. PubMed

    Erlotinib

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

Reported for Usnea but not commonly for Erlotinib: yellowing of the skin or eyes and stomach pain.

Effects for Erlotinib come from the ADVERSE REACTIONS section of its FDA label; effects for Usnea come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 12,442 voluntary FDA FAERS reports for Erlotinib 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.

How to take them

Some Erlotinib Products Have a Food Rule — Usnea Should Not Break It

At least one FDA label for a product containing Erlotinib says to take it on an empty stomach. Most supplements — Usnea included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Erlotinib on its own and move Usnea to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Erlotinib products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

Recommended Dose – NSCLC The recommended daily dose of erlotinib tablets for NSCLC is 150 mg taken on an empty stomach, i.e., at least one hour before or two hours after the ingestion of food.

From the Dosage and Administration section of the FDA label we read for Erlotinib — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

Everything else you take

See Every Supplement That Interacts With Erlotinib

This page covers Usnea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Erlotinib page lists 18 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Bilberry (moderate), Coffee Charcoal (moderate), European Mandrake (moderate) and Glucomannan (moderate).

By severity: 1 major · 8 moderate · 9 minor.

From our pharmacist’s overview on the Erlotinib page

“Activated charcoal is the entry I would flag first for anyone taking erlotinib (Tarceva), an oral targeted therapy for certain lung cancers. Charcoal can adsorb the drug in the gut and cut how much reaches the bloodstream, and with a cancer pill, less absorbed means less cancer fought.”

Reviewed by 2 · Jul 18, 2026

Open the Erlotinib interaction page

One more smart check

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

We hold 138 real supplement products containing Usnea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Usnea. Even though Usnea itself has no known interaction with Erlotinib, 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 Usnea and Erlotinib 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 Usnea
Top half

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

29 days ago today
Medication Erlotinib
Steady interest

#2,082 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 Usnea reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 27, 2026. The Usnea and Erlotinib records this page draws on were last updated July 11, 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 Usnea

What is Usnea?

  • Sore throat
  • Skin and wound care
  • Respiratory infections
  • Urinary tract support
  • Antimicrobial/antifungal
  • Immune support

Usnea is a lichen used in traditional herbal medicine, mainly for sore throats, skin infections, and as a general antimicrobial. Laboratory studies suggest its main compound, usnic acid, can fight bacteria and fungi, but good human studies are lacking. Oral use of concentrated usnic acid has been linked to serious liver injury, so caution is important.

Usnea barbata · Parmeliaceae · Whole lichen (thallus) · Tincture, capsules, tea, throat sprays, topical salves

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

Usnea: dosing

There is no well-established standardized dose for Usnea. Products vary widely in strength and in how much usnic acid they contain, which makes safe dosing hard to define.If you choose to use Usnea, follow the directions on the product label and do not exceed them.

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

Read the full Usnea monograph & all interactions
Medication

About Erlotinib

What Is Erlotinib Used For?

Brand name: Tarceva

Erlotinib tablets are used to treat metastatic non-small cell lung cancer (NSCLC) in patients whose tumors carry specific gene changes — EGFR exon 19 deletions or exon 21 (L858R) mutations — confirmed by an FDA-approved test. It can be used as a first-line treatment, as maintenance therapy, or after at least one prior chemotherapy has stopped working.

Erlotinib tablets are also used for the first-line treatment of locally advanced, unresectable, or metastatic pancreatic cancer — but only in combination with another chemotherapy drug called gemcitabine. Erlotinib is not recommended alongside platinum-based chemotherapy regimens.

Most-Reported Side Effects for Erlotinib

From FAERS, the FDA’s public side-effect reporting system (12,441 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 1,339 reports
Rash 1,317 reports
Malignant neoplasm progression 890 reports
Fatigue 718 reports
Nausea 696 reports
See full Erlotinib drug information
Keep checking

Other Drugs & Usnea

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Usnea list.

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

Usnea References

The 10 references that drive our Usnea 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. Favreau JT, Ryu Ml, Braunstein G, et al. Severe hepatotoxicity associated with the dietary supplement LipoKinetix. Ann Intern Med 2002;136:590-5. PubMed
  2. Ingolfsdottir K. Usnic acid. Phytochemistry 2002;61:729-36.
  3. Scirpa, P., Scambia, G., Masciullo, V., Battaglia, F., Foti, E., Lopez, R., Villa, P., Malecore, M., and Mancuso, S. [A zinc sulfate and usnic acid preparation used as post-surgical adjuvant therapy in genital lesions by Human Papillomavirus]. Minerva Gin
  4. Mitchell, J. C. Allergy to lichens. Allergic contact dermatitis from usnic acid produced by lichenized fungi. Arch Dermatol 1965;92(2):142-146.
  5. Durazo, F. A., Lassman, C., Han, S. H., Saab, S., Lee, N. P., Kawano, M., Saggi, B., Gordon, S., Farmer, D. G., Yersiz, H., Goldstein, R. L., Ghobrial, M., and Busuttil, R. W. Fulminant liver failure due to usnic acid for weight loss. Am.J Gastroenterol. PubMed
  6. Neff, G. W., Reddy, K. R., Durazo, F. A., Meyer, D., Marrero, R., and Kaplowitz, N. Severe hepatotoxicity associated with the use of weight loss diet supplements containing ma huang or usnic acid. J Hepatol. 2004;41(6):1062-1064. PubMed
  7. Hsu, L. M., Huang, Y. S., Chang, F. Y., and Lee, S. D. 'Fat burner' herb, usnic Acid, induced acute hepatitis in a family. J Gastroenterol.Hepatol. 2005;20(7):1138-1139. PubMed
  8. Arneborn, P., Jansson, A., and Bottiger, Y. [Acute hepatitis in a woman after intake of slimming pills bought via Internet]. Lakartidningen 7-11-2005;102(28-29):2071-2072.
  9. Sanchez, W., Maple, J. T., Burgart, L. J., and Kamath, P. S. Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc 2006;81(4):541-544. PubMed
  10. Rafanelli, S., Bacchilega, R., Stanganelli, I., and Rafanelli, A. Contact dermatitis from usnic acid in vaginal ovules. Contact Dermatitis 1995;33(4):271-272. 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 Usnea and Erlotinib Together: Common Questions

Is it safe to take Usnea with Erlotinib?
We do not list a known interaction between Usnea and Erlotinib. 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 Usnea and Erlotinib have any of the same side effects?
Yes — our sources link each of them separately to 5 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.
Should I take Usnea and Erlotinib at the same time of day?
At least one FDA label for a product containing Erlotinib says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Erlotinib on its own and move Usnea to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
Does Erlotinib interact with any supplements?
Yes. Erlotinib has documented interactions with 18 supplements in our database — Usnea is not one of them. The Erlotinib 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

Usnea monograph Uses, safety profile, and every drug interaction in one place Erlotinib drug information The full plain-English guide to this medication Erlotinib supplement interactions Every supplement checked against Erlotinib, 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 10 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Erlotinib and Usnea?

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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.