Drug & supplement interaction

Lysine + Ethosuximide

Ethosuximide brand name: Zarontin.

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 Ethosuximide 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

Lysine and Ethosuximide

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 Ethosuximide 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 Ethosuximide and Lysine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Ethosuximide

Interactions in our licensed database are recorded against drug classes, not just single drug names. Ethosuximide is filed under 7 classifications — including anticonvulsants, cytochrome p450 3a4 (cyp3a4) inducers, cns depressants. Lysine has documented interactions with 1 drug class — the most serious being 5-ht4 agonists (minor) — and none of Ethosuximide’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 — Ethosuximide 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. Ethosuximide)
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

No Interaction Found — But Data Suggests Lysine and Ethosuximide 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.

  • Stomach pain / Diarrhea Additional detail

    Lysine

    “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

    Ethosuximide

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

Reported for Lysine but not commonly for Ethosuximide: kidney problems and stomach upset.

Effects for Ethosuximide come from the ADVERSE REACTIONS section of its FDA label; effects for Lysine come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 2,490 voluntary FDA FAERS reports for Ethosuximide 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 Ethosuximide

This page covers Lysine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ethosuximide page lists 226 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), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Grapefruit (major).

By severity: 9 major · 179 moderate · 38 minor.

From our pharmacist’s overview on the Ethosuximide page

“Ethosuximide (Zarontin) prevents absence seizures, and a steady blood level is what keeps them away, so I treat this list of 226 interacting supplements and herbs with real care, especially the nine rated major. More than half of the entries can change how the liver clears the drug; grapefruit can raise its level while St.”

Reviewed by 2 · Jul 18, 2026

Open the Ethosuximide 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 Ethosuximide, 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 Ethosuximide 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 Ethosuximide
Steady interest

#2,341 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 Ethosuximide 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 Ethosuximide

What Is Ethosuximide Used For?

Brand name: Zarontin

Ethosuximide — sold as Zarontin and also available as generic Ethosuximide — is used to control absence (petit mal) epilepsy. Absence seizures are brief episodes where a person loses awareness for a few seconds, often mistaken for daydreaming.

Both Zarontin and Ethosuximide products (capsule and oral solution forms) are approved for this use. Either may also be used alongside other seizure medicines when a patient has absence seizures together with other types of epilepsy.

Most-Reported Side Effects for Ethosuximide

From FAERS, the FDA’s public side-effect reporting system (2,490 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Seizure 367 reports
Somnolence 157 reports
Generalised tonic-clonic seizure 149 reports
Petit mal epilepsy 118 reports
Treatment failure 116 reports
See full Ethosuximide 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 Ethosuximide, 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 Ethosuximide Together: Common Questions

Is it safe to take Lysine with Ethosuximide?
We do not list a known interaction between Lysine and Ethosuximide. 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 Lysine and Ethosuximide 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.
How was the Lysine and Ethosuximide combination checked?
Interactions in our licensed database are recorded against drug classes. Ethosuximide is filed under 7 classifications, and Lysine has documented interactions with 1 drug class — none of Ethosuximide'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 — Ethosuximide 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 Ethosuximide interact with any supplements?
Yes. Ethosuximide has documented interactions with 226 supplements in our database — Lysine is not one of them. The Ethosuximide 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 Ethosuximide drug information The full plain-English guide to this medication Ethosuximide supplement interactions Every supplement checked against Ethosuximide, 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 Ethosuximide 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.