Drug & supplement interaction

Lysine + Doxepin

Doxepin brand names: Sinequan, Doxepin, Zonalon.

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 Lysine and Doxepin 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.

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Interaction report

Lysine and Doxepin

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 Doxepin and Lysine 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.

Lysine safety at a glance

Lysine overall Use caution Generally well tolerated at typical doses, but high amounts may cause stomach upset and long-term safety is not well studied.
Pregnancy Use caution Lysine from food is fine, but supplement safety in pregnancy is not well studied, so check with your doctor first.
Breastfeeding Use caution There is not enough reliable information on supplement use while breastfeeding, so caution is advised.

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

Still wondering about combining Doxepin and Lysine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Doxepin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Doxepin is filed under 10 classifications — including tricyclic antidepressants (tcas), antidepressant drugs, qt interval-prolonging drugs. Lysine has documented interactions with 1 drug class — the most serious being 5-ht4 agonists (minor) — and none of Doxepin’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

Lysine Does Interact With Other Medications

Lysine has 1 minor known drug interaction in our database — Doxepin isn’t one of them. If you take anything else, check it against the full list below.

Minor 1 No known interaction 2,829 (incl. Doxepin)
Taking anything else?

Check Another of Your Medications Against Lysine

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

What to actually watch for

What Lysine Itself Has Been Linked To

This is not an interaction — nothing below involves Doxepin. It is the side-effect record for Lysine on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Lysine, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • Kidney problems Worth acting on Additional detail

    “There is one case report of oral lysine use associated with tubulointerstitial nephritis progressing to chronic renal failure in a 44-year old female.”

    Lysine · Natural Medicines adverse-effect record, reported in kidney failure.

    1 source cited
    1. 1121. Lo JC, Chertow GM, Rennke H, Seifter JL. Fanconi's syndrome and tubulointerstitial nephritis in association with L-lysine ingestion. Am J Kidney Dis 1996;28:614-7. PubMed
  • Stomach upset / Stomach pain / Diarrhea Additional detail

    “Orally, lysine has been reported to cause diarrhea and abdominal pain, including dyspepsia.”

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

    5 sources cited
    1. 1114. Thein DJ, Hurt WC. Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis. Oral Surg Oral Med Oral Pathol 1984;58:659-66. PubMed
    2. 1115. McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis 1984;34:366-73.
    3. 1116. DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol 1984;120:48-51. DOI
    4. 1118. Milman N, Scheibel J, Jessen O. Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study. Acta Derm Venereol 1980;60:85-7.
    5. 1120. Griffith RS, Walsh DE, Myrmel KH, et al. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica 1987;175:183-90. DOI

Everything above comes from the Natural Medicines adverse-effect record for Lysine — expand a row for the licensed statement it rests on. We haven’t matched Doxepin to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Doxepin.

Overlapping uses

What Doxepin Is Prescribed For, and What Lysine Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Doxepin is a prescription medicine with approved uses on its FDA label. Lysine is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Doxepin is prescribed for: This product is marketed to temporarily relieve occasional trouble sleeping when it's brought on by anxiety, restlessness, stress, or sensitivity to caffeine. It is a homeopathic remedy — meaning its claims are based on traditional homeopathic practice, not accepted medical evidence, and it has not been evaluated by the FDA for effectiveness.

Lysine has been studied for:

  • Stress studied, not established Lysine has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Lysine for stress

    Limited clinical research in economically disadvantaged populations shows that fortifying wheat with lysine may reduce stress and anxiety.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Doxepin on your own; if you are taking Lysine for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Doxepin

This page covers Lysine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Doxepin page lists 186 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), American Hellebore (major), Arsenic (major) and Beer (major).

By severity: 15 major · 145 moderate · 26 minor.

From our pharmacist’s overview on the Doxepin page

“Doxepin is a sedating tricyclic prescribed for depression, anxiety, and often sleep itself, and the people taking it tend to shop the same shelf where the trouble sits. Of the 186 supplements on file, 78 deepen its drowsiness, with alcohol (beer and wine carry major, well-documented ratings) and kava the clearest examples, and I would…”

Reviewed by 2 · Jul 18, 2026

Open the Doxepin interaction page

One more smart check

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

We hold 3,540 real supplement products containing Lysine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lysine. Even though Lysine itself has no known interaction with Doxepin, 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 Lysine and Doxepin 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 Lysine
Top 5%

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

29 days ago today
Medication Doxepin
Steady interest

#1,468 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 Lysine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Lysine and Doxepin 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 Lysine

What is Lysine?

  • Cold sores (herpes labialis)
  • Genital herpes outbreaks
  • Supporting protein and collagen formation
  • Calcium absorption support
  • General nutritional supplement

Lysine is an essential amino acid your body cannot make on its own, so it must come from food or supplements. People most often take extra lysine to try to prevent or shorten cold sores, but the evidence is mixed and far from conclusive. For most healthy people who eat enough protein, supplements are likely unnecessary, but they are generally considered low-risk at typical doses.

Amino acid (L-lysine) · Tablets, capsules, powder, topical creams (often combined with other ingredients)

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

Lysine: dosing

There is no single official supplement dose of lysine for any health condition, and a truly standardized dose has not been established for uses like cold sores. Products vary widely in how much they contain.The best approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full Lysine monograph & all interactions
Medication

About Doxepin (Insomnia)

What Is Doxepin (Insomnia) Used For?

Brand names: Sinequan, Doxepin, Zonalon

This product is marketed to temporarily relieve occasional trouble sleeping when it's brought on by anxiety, restlessness, stress, or sensitivity to caffeine.

It is a homeopathic remedy — meaning its claims are based on traditional homeopathic practice, not accepted medical evidence, and it has not been evaluated by the FDA for effectiveness.

Most-Reported Side Effects for Doxepin

From FAERS, the FDA’s public side-effect reporting system (12,553 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Toxicity to various agents 988 reports
Completed suicide 828 reports
Fatigue 793 reports
Nausea 679 reports
Headache 642 reports
See full Doxepin (Insomnia) drug information
Keep checking

Other Drugs & Lysine

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

0Major
0Moderate
1Minor
2,828No known interaction
1 Minor 2,828 No interaction
Minor

1 interaction

No interaction 2,828 drugs checked — show the list

We also checked Lysine 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 Lysine list.

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

Lysine References

The 7 references that drive our Lysine 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. Thein DJ, Hurt WC. Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis. Oral Surg Oral Med Oral Pathol 1984;58:659-66. PubMed
  2. McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis 1984;34:366-73.
  3. DiGiovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol 1984;120:48-51. DOI
  4. Milman N, Scheibel J, Jessen O. Lysine prophylaxis in recurrent herpes simplex labialis: a double-blind, controlled crossover study. Acta Derm Venereol 1980;60:85-7.
  5. Griffith RS, Walsh DE, Myrmel KH, et al. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica 1987;175:183-90. DOI
  6. Lo JC, Chertow GM, Rennke H, Seifter JL. Fanconi's syndrome and tubulointerstitial nephritis in association with L-lysine ingestion. Am J Kidney Dis 1996;28:614-7. PubMed
  7. Smriga M, Torii K. L-Lysine acts like a partial serotonin receptor 4 antagonist and inhibits serotonin-mediated intestinal pathologies and anxiety in rats. Proc Natl Acad Sci U S A. 2003 Dec 23;100(26):15370-5.

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 Lysine and Doxepin Together: Common Questions

Is it safe to take Lysine with Doxepin?
We do not list a known interaction between Lysine and Doxepin. 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.
Are Lysine and Doxepin used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Lysine in each. That is a conversation for your prescriber, especially if Doxepin is being adjusted to a target.
How was the Lysine and Doxepin combination checked?
Interactions in our licensed database are recorded against drug classes. Doxepin is filed under 10 classifications, and Lysine has documented interactions with 1 drug class — none of Doxepin'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 Lysine interact with any other medications?
Yes. Lysine has 1 documented drug interaction in our database — Doxepin 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 Doxepin interact with any supplements?
Yes. Doxepin has documented interactions with 186 supplements in our database — Lysine is not one of them. The Doxepin 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

Lysine monograph Uses, safety profile, and every drug interaction in one place Doxepin (Insomnia) drug information The full plain-English guide to this medication Doxepin supplement interactions Every supplement checked against Doxepin, 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 7 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Doxepin and Lysine?

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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.