Drug & supplement interaction

Guaiac Wood + Erlotinib

Erlotinib brand name: Tarceva.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Oct 4, 2026
The bottom line No known interaction

We found no known interaction between Guaiac Wood 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

Guaiac Wood 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 Guaiac Wood 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.

Guaiac Wood safety at a glance

Guaiac Wood overall Use caution Mostly used externally or as a scent; little safety data for internal use.
Pregnancy Avoid Not enough safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid No reliable safety data while breastfeeding, so avoid use.

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

Still wondering about combining Erlotinib and Guaiac Wood? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Erlotinib

Interactions in our licensed database are recorded against drug classes, not just single drug names. Erlotinib is filed under 2 classifications — including oral drugs. Guaiac Wood has documented interactions with 1 drug class — the most serious being lithium (moderate) — and none of Erlotinib’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

Guaiac Wood Does Interact With Other Medications

Guaiac Wood has 1 moderate known drug interaction in our database — Erlotinib 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. Erlotinib)
Taking anything else?

Check Another of Your Medications Against Guaiac Wood

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

What to actually watch for

No Interaction Found — But Data Suggests Guaiac Wood and Erlotinib May Share a Side Effect

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 reported in 10.8% of FDA reports for Erlotinib Additional detail

    Guaiac Wood

    “Orally, high doses of guaiac wood can cause diarrhea, gatroenteritis, or intestinal colic (18).”

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

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    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 ›

Effects for Erlotinib come from the ADVERSE REACTIONS section of its FDA label; effects for Guaiac Wood come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 12,441 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 — Guaiac Wood Should Not Break It

At least one FDA label for a product containing Erlotinib says to take it on an empty stomach. Most supplements — Guaiac Wood 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 Guaiac Wood 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 Guaiac Wood 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

How much people look this up

Where Guaiac Wood 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 Guaiac Wood
Steady interest

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

29 days ago today
Medication Erlotinib
Top half

#1,079 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 Guaiac Wood reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Guaiac Wood and Erlotinib 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 Guaiac Wood

What is Guaiac Wood?

  • Fragrance in perfumes and soaps
  • Aromatherapy and relaxation
  • Traditional anti-inflammatory remedy
  • Skin care products
  • Traditional joint and arthritis support

Guaiac wood is mainly valued for its sweet, smoky-rosy aroma and is used widely as a fragrance ingredient and in aromatherapy. There is very little high-quality human research supporting any health or medical benefit, so it should be thought of as a scent rather than a proven remedy. If you want to use it, talk to your pharmacist or doctor first, and avoid taking it by mouth.

Bulnesia sarmientoi · Zygophyllaceae · Wood and essential oil (also called guaiacwood oil) · Essential oil, aromatherapy blends, soaps and perfumes; sometimes wood chips or resin

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

Guaiac Wood: dosing

There is no established or standardized medical dose for guaiac wood. It is most often used in small amounts as a fragrance in finished products such as soaps, perfumes, or aromatherapy diffuser blends.If you choose to use a guaiac wood product, follow the directions on the label and dilute essential oils properly before applying them to skin.

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

Read the full Guaiac Wood monograph & all interactions
Medication

About Erlotinib

What Is Erlotinib Used For?

Brand name: Tarceva

Erlotinib treats metastatic non-small cell lung cancer (NSCLC) when the tumor has certain EGFR gene changes (exon 19 deletions or exon 21 L858R mutations), found by an FDA-approved test. It can be used first, as maintenance, or after at least one prior chemotherapy regimen has stopped working.

Erlotinib is also used with gemcitabine as first-line treatment for locally advanced, unresectable or metastatic pancreatic cancer. These uses are listed for the erlotinib tablet products.

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 & Guaiac Wood

Browse every other medication we’ve checked against Guaiac Wood — 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 Guaiac Wood 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 Guaiac Wood list.

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

Guaiac Wood References

The 1 references that drive our Guaiac Wood 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. 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.

Pharmacist Counseling Corner

Taking Guaiac Wood and Erlotinib Together: Common Questions

Is it safe to take Guaiac Wood with Erlotinib?
We do not list a known interaction between Guaiac Wood 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 Guaiac Wood and Erlotinib have any of the same side effects?
Yes — our sources link each of them separately to one 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 Guaiac Wood 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 Guaiac Wood 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.
How was the Guaiac Wood and Erlotinib combination checked?
Interactions in our licensed database are recorded against drug classes. Erlotinib is filed under 2 classifications, and Guaiac Wood has documented interactions with 1 drug class — none of Erlotinib'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 Guaiac Wood interact with any other medications?
Yes. Guaiac Wood has 1 documented drug interaction in our database — Erlotinib 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 Erlotinib interact with any supplements?
Yes. Erlotinib has documented interactions with 18 supplements in our database — Guaiac Wood 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

Guaiac Wood 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 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Erlotinib and Guaiac Wood?

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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.