Drug & supplement interaction

L-citrulline + Erlotinib

Erlotinib brand name: Tarceva.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between L-citrulline 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

L-citrulline 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 L-citrulline 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.

L-citrulline safety at a glance

L-citrulline overall Use caution Generally well tolerated in healthy adults, but long-term safety is not fully studied.

Pregnancy Avoid There is not enough safety data, so it is best to avoid supplements during pregnancy.

Breastfeeding Avoid Safety while breastfeeding is unknown, so avoid supplemental use.

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

Still wondering about combining Erlotinib and L-citrulline? 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. L-citrulline has documented interactions with 2 drug classes — the most serious being antihypertensive drugs (moderate) and phosphodiesterase-5 inhibitors (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

L-citrulline Does Interact With Other Medications

L-citrulline has 178 moderate known drug interactions in our database — Erlotinib isn’t one of them. If you take anything else, check it against the full list below.

Moderate 178 No known interaction 2,652 (incl. Erlotinib)

Taking anything else?

Check Another of Your Medications Against L-citrulline

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

What to actually watch for

No Interaction Found — But Data Suggests L-citrulline 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.

Cough Additional detail
L-citrulline
“Orally, 2 of 25 patients with pulmonary hypertension reported cough while taking 1 gram of powdered L-citrulline in water daily.”

L-citrulline · Natural Medicines adverse-effect record, reported in cough.
1 source cited

94963. Sharif Kashani B, Tahmaseb Pour P, Malekmohammad M, et al. Oral l-citrulline malate in patients with idiopathic pulmonary arterial hypertension and Eisenmenger Syndrome: a clinical trial. J Cardiol 2014;64:231-5. PubMed
Erlotinib

Listed in the ADVERSE REACTIONS section of the FDA label for Erlotinib. Read the label on DailyMed ›
Stomach upset Additional detail
L-citrulline
“Orally, gastrointestinal intolerance, stomach discomfort, and heartburn have been reported with L-citrulline use.”

L-citrulline · Natural Medicines adverse-effect record, reported in dyspepsia.
3 sources cited

94955. Balderas-Munoz K, Castillo-Martínez L, Orea-Tejeda A, et al. Improvement of ventricular function in systolic heart failure patients with oral L-citrulline supplementation. Cardiol J 2012;19:612-7. PubMed

94963. Sharif Kashani B, Tahmaseb Pour P, Malekmohammad M, et al. Oral l-citrulline malate in patients with idiopathic pulmonary arterial hypertension and Eisenmenger Syndrome: a clinical trial. J Cardiol 2014;64:231-5. PubMed

94966. Pérez-Guisado J, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res 2010;24:1215-22. PubMed
Erlotinib

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

Reported for L-citrulline but not commonly for Erlotinib: raised blood pressure, heartburn and swelling.

Effects for Erlotinib come from the ADVERSE REACTIONS section of its FDA label; effects for L-citrulline 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 — L-citrulline Should Not Break It

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

From our Q&A

Questions About L-citrulline or Erlotinib

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

This page covers L-citrulline 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 L-citrulline as Part of a Dietary Supplement Product? Check It for Interactions

We hold 63 real supplement products containing L-citrulline, each one broken down to its full ingredient list — and combination products often carry several ingredients besides L-citrulline. Even though L-citrulline 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 L-citrulline 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 L-citrulline

Top half

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

29 days ago today

Medication Erlotinib

Top half

#1,386 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 L-citrulline reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The L-citrulline 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About L-citrulline

What is L-citrulline?

Exercise performance
Muscle soreness and fatigue
Blood flow and circulation
Erectile dysfunction
Blood pressure support

L-citrulline is an amino acid that the body turns into L-arginine to help make nitric oxide, which relaxes blood vessels and may improve blood flow. It is popular for exercise performance and circulation, but the evidence is mixed and most benefits are modest. It appears generally well tolerated, but talk to your pharmacist or doctor before starting, especially if you have a health condition or are pregnant.

Amino acid (made by the body and found in foods; supplements are usually made by fermentation) · Powder, capsules, tablets; also sold as citrulline malate

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

L-citrulline: dosing

There is no official standardized dose of L-citrulline, and the right amount can depend on the form (plain L-citrulline versus citrulline malate) and the reason for use. Doses used in studies vary widely.Because of this, the best approach is to follow the directions on the product label and start with the lowest suggested amount.

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

Read the full L-citrulline 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 (12,442 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 1,341 reports

Rash 1,316 reports

Malignant neoplasm progression 891 reports

Fatigue 719 reports

Nausea 696 reports

See full Erlotinib drug information

Keep checking

Other Drugs & L-citrulline

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

0Major

178Moderate

0Minor

2,651No known interaction

178 Moderate 2,651 No interaction

Moderate

178 interactions

Showing 60 of 178 moderate interactions — see all 178 on the L-citrulline page.

No interaction 2,651 drugs checked — show the list

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

Showing the 60 most looked-up of 2,651 medications checked with no known interaction — see the full L-citrulline list.

See the full L-citrulline interactions page

See every supplement checked against Erlotinib, ranked by severity

Evidence & sources

L-citrulline References

The 8 references that drive our L-citrulline 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.

Cheng JW, Balwin SN. L-arginine in the management of cardiovascular diseases. Ann Pharmacother 2001;35:755-64. PubMed
Schwedhelm E, Maas R, Freese R, et al. Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. Br J Clin Pharmacol 2008;65:51-9. PubMed
Romero MJ, Platt DH, Caldwell RB, Caldwell RW. Therapeutic use of citrulline in cardiovascular disease. Cardiovasc Drug Rev 2006;24:275-90. PubMed
Balderas-Munoz K, Castillo-Martínez L, Orea-Tejeda A, et al. Improvement of ventricular function in systolic heart failure patients with oral L-citrulline supplementation. Cardiol J 2012;19:612-7. PubMed
Sharif Kashani B, Tahmaseb Pour P, Malekmohammad M, et al. Oral l-citrulline malate in patients with idiopathic pulmonary arterial hypertension and Eisenmenger Syndrome: a clinical trial. J Cardiol 2014;64:231-5. PubMed
Pérez-Guisado J, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res 2010;24:1215-22. PubMed
Mirenayat MS, Moradi S, Mohammadi H, Rouhani MH. Effect of L-citrulline supplementation on blood pressure: a systematic review and meta-analysis of clinical trials. Curr Hypertens Rep. 2018;20(11):98. PubMed
Xu Z, Liu C, Liu S, Zhou Z. Comparison of efficacy and safety of daily oral L-arginine and PDE5Is alone or combination in treating erectile dysfunction: A systematic review and meta-analysis of randomised controlled trials. Andrologia. 2021:e14007. 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 L-citrulline and Erlotinib Together: Common Questions

Is it safe to take L-citrulline with Erlotinib?

We do not list a known interaction between L-citrulline 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 L-citrulline and Erlotinib have any of the same side effects?

Yes — our sources link each of them separately to 2 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 L-citrulline 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 L-citrulline 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 L-citrulline and Erlotinib combination checked?

Interactions in our licensed database are recorded against drug classes. Erlotinib is filed under 2 classifications, and L-citrulline has documented interactions with 2 drug classes — 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 L-citrulline interact with any other medications?

Yes. L-citrulline has 178 documented drug interactions 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 — L-citrulline 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

L-citrulline 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 8 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Erlotinib and L-citrulline?

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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.