Drug & supplement interaction

Lemon Balm + Fosphenytoin Sodium

Fosphenytoin Sodium brand name: Sesquient.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Lemon Balm has a moderate interaction with Fosphenytoin Sodium. Theoretically, concomitant use of lemon balm might have additive effects with CNS depressant drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceB
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Lemon Balm and Fosphenytoin Sodium

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CNS DEPRESSANTS

Why this applies to Fosphenytoin Sodium

Fosphenytoin Sodium falls under CNS DEPRESSANTS — the group Lemon Balm interacts with.

Theoretically, concomitant use of lemon balm might have additive effects with CNS depressant drugs.
Lemon balm seems to have CNS depressant activity in animals and in humans.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist with lemon balm and fosphenytoin (Sesquient). Fosphenytoin is a seizure medicine that your body quickly converts into phenytoin once it's in your system. It can already make people feel drowsy, dizzy, or a bit unsteady on their feet. Lemon balm has a mild calming, sedative quality of its own, so taking the two together could stack those effects and leave you feeling sleepier or more lightheaded than usual.

This is mostly a theoretical concern based on small studies and animal research, not strong human data, so it's not a reason to panic. Still, since fosphenytoin is a serious seizure drug, I'd run any lemon balm supplement past your pharmacist or doctor first and watch for extra grogginess.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Kennedy DO, Scholey AB, Tildesley NT, et al. Modulation of mood and cognitive performance following acute administration of Melissa officinalis (lemon balm). Pharmacol Biochem Behav 2002;72:953-64. PubMed
  2. Soulimani R, Fleurentin J, Mortier F, et al. Neurotropic action of the hydroalcoholic extract of Melissa officinalis in the mouse. Planta Med. 1991 Apr;57:105-9.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Lemon Balm Also Interacts With Other Medications

Lemon Balm has 263 moderate known drug interactions in our database — the Fosphenytoin Sodium one above is one of them. If you take anything else, check it against the full list below.

Moderate 263 No known interaction 2,567 (incl. Fosphenytoin Sodium)
Taking anything else?

Check Another of Your Medications Against Lemon Balm

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

From our Q&A

Questions About Lemon Balm or Fosphenytoin Sodium

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Lemon Balm or Fosphenytoin Sodium, 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 Fosphenytoin Sodium

This page covers Lemon Balm only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin Sodium page lists 212 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 14 major · 179 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin Sodium page

“Fosphenytoin sodium (Sesquient) converts to phenytoin in the body, and phenytoin is unforgiving about blood levels. A little too low invites seizures, a little too high brings toxicity.”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin Sodium interaction page

One more smart check

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

We hold 2,076 real supplement products containing Lemon Balm, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Lemon Balm. Your product may carry other ingredients that interact with Fosphenytoin Sodium too, on top of Lemon Balm — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Lemon Balm and Fosphenytoin Sodium 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 Lemon Balm
Top 10%

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

29 days ago today
Medication Fosphenytoin Sodium
Top 5%

#110 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.

Supplement

About Lemon Balm

What is Lemon Balm?

Lemon Balm
  • Anxiety and stress
  • Sleep problems
  • Digestive upset
  • Cold sores
  • Restlessness or nervousness

Lemon balm is a gentle, lemon-scented mint-family herb traditionally used to ease stress, support sleep, and calm digestion, and topically for cold sores. Early studies are promising but generally small, so the evidence is limited. It is usually well tolerated for most adults, but pregnant or breastfeeding people should check with a doctor or pharmacist first.

Read the full Lemon Balm monograph & all interactions
Keep checking

Other Drugs & Lemon Balm

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

0Major
263Moderate
0Minor
2,566No known interaction
263 Moderate 2,566 No interaction
Moderate

263 interactions

Showing 60 of 263 moderate interactions — see all 263 on the Lemon Balm page.

No interaction 2,566 drugs checked — show the list

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

Showing the 60 most looked-up of 2,566 medications checked with no known interaction — see the full Lemon Balm list.

See the full Lemon Balm interactions page
See every supplement checked against Fosphenytoin Sodium, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Lemon Balm monograph › Uses, safety, and every drug interaction in one place Fosphenytoin Sodium supplement interactions › Every supplement checked against Fosphenytoin Sodium, 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 Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Lemon Balm and Fosphenytoin Sodium Together: Common Questions

Can you take Lemon Balm with Fosphenytoin Sodium?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Lemon Balm and Fosphenytoin Sodium interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Fosphenytoin Sodium and Lemon Balm?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.