Drug & supplement interaction

Shellac + 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 Shellac 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

Shellac 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 Shellac 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 Shellac at all — not against Lapatinib, 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.

Shellac safety at a glance

Shellac overall Use caution Generally regarded as safe as a coating in small amounts, but it is insect-derived and rare reactions can occur.
Pregnancy Use caution Likely fine in the tiny amounts used as a coating, but there is little specific safety data, so check with your doctor.
Breastfeeding Use caution Little specific data exists; the small amounts in coatings are unlikely to be a concern but caution is wise.

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

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

No Interaction Found — But Data Suggests Shellac and Lapatinib 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.

  • A skin rash reported in 6.9% of FDA reports for Lapatinib Additional detail

    Shellac

    “Topically, there are numerous reports of allergic contact dermatitis and allergic contact cheilitis associated with shellac. Most cases of allergic dermatitis are related to shellac in mascara, especially Maybelline Great Lash mascara. However, cases of allergic contact dermatitis associated with shellac in tattoo ink and shellac in hair spray have been reported.”

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

    6 sources cited
    1. 104260. González-Villanueva I, Hispn Ocete P, Silvestre Salvador JF. Allergic contact dermatitis caused by a black tattoo ink in a patient allergic to shellac. Contact Dermatitis. 2016;75(4):247-8. PubMed
    2. 104262. Shaw T, Oostman H, Rainey D, Storrs F. A rare eyelid dermatitis allergen: shellac in a popular mascara. Dermatitis. 2009;20(6):341-5. DOI
    3. 104263. Gallo R, Marro I, Pavesi A. Allergic contact dermatitis from shellac in mascara. Contact Dermatitis. 2005;53(4):238. PubMed
    4. 104264. Strauss RM, Orton DI. Allergic contact cheilitis in the United Kingdom: a retrospective study. Am J Contact Dermat. 2003;14(2):75-7. DOI
    5. 104265. Orton DI, Salim A, Shaw S. Allergic contact cheilitis due to shellac. Contact Dermatitis. 2001;44(4):250. PubMed
    6. 112297. Navarro-Triviño FJ. Allergic contact dermatitis from shellac in an ecological hair spray occurring in a patient with frontal fibrosing alopecia. Contact Dermatitis 2022;86(6):544-545. 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 ›

Effects for Lapatinib come from the ADVERSE REACTIONS section of its FDA label; effects for Shellac 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.

Everything else you take

See Every Supplement That Interacts With Lapatinib

This page covers Shellac 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

How much people look this up

Where Shellac 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 Shellac
Steady interest

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

29 days ago today
Medication Lapatinib
Steady interest

#2,248 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 Shellac reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Shellac 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 Shellac

What is Shellac?

Shellac
  • Coating for tablets and capsules
  • Glaze on candy and chocolates
  • Protective film over pills and supplements
  • Enteric-style coating to delay dissolving
  • Shiny coating on fruits and confections

Shellac is a natural resin made from the secretions of the lac insect, and it is used mainly as a glaze or coating on pills, candy, and some supplements rather than as an active ingredient you take for a health benefit. In the small amounts used for coatings it is generally considered safe for most people, but those avoiding insect-derived products or with known sensitivities may want to steer clear.

Resinous secretion of the lac insect (Kerria lacca) · Tablet and capsule coatings, candy and pill glazes, food glaze (confectioner's glaze)

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

Shellac: dosing

There is no established therapeutic dose for shellac, because it is not taken as an active ingredient. It is used in whatever small amount is needed to coat or glaze a product.If you are choosing a supplement, you do not need to dose shellac itself.

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

Read the full Shellac 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 & Shellac

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

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

Shellac References

The 8 references that drive our Shellac 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. González-Villanueva I, Hispn Ocete P, Silvestre Salvador JF. Allergic contact dermatitis caused by a black tattoo ink in a patient allergic to shellac. Contact Dermatitis. 2016;75(4):247-8. PubMed
  3. Shaw T, Oostman H, Rainey D, Storrs F. A rare eyelid dermatitis allergen: shellac in a popular mascara. Dermatitis. 2009;20(6):341-5. DOI
  4. Gallo R, Marro I, Pavesi A. Allergic contact dermatitis from shellac in mascara. Contact Dermatitis. 2005;53(4):238. PubMed
  5. Strauss RM, Orton DI. Allergic contact cheilitis in the United Kingdom: a retrospective study. Am J Contact Dermat. 2003;14(2):75-7. DOI
  6. Orton DI, Salim A, Shaw S. Allergic contact cheilitis due to shellac. Contact Dermatitis. 2001;44(4):250. PubMed
  7. Navarro-Triviño FJ. Allergic contact dermatitis from shellac in an ecological hair spray occurring in a patient with frontal fibrosing alopecia. Contact Dermatitis 2022;86(6):544-545. PubMed
  8. Mercader-García P, Ruiz-Gonzalez I, Gonzalez-Perez R, Sanz-Sanchez T, Sanchez-Pérez J, Borrego L; en representación de REIDAC. Contact Allergy to Shellac. Retrospective Cross-Sectional Study With Data From the Spanish Registry of Research in Contact Derma

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 Shellac and Lapatinib Together: Common Questions

Is it safe to take Shellac with Lapatinib?
We do not list a known interaction between Shellac 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 Shellac and Lapatinib 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.
Does Lapatinib interact with any supplements?
Yes. Lapatinib has documented interactions with 143 supplements in our database — Shellac 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

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

Still Have a Question About Lapatinib and Shellac?

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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.