Drug & supplement interaction

Beer + Fosphenytoin

Fosphenytoin brand name: Cerebyx.

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

Fosphenytoin falls into 3 drug categories that Beer can interact with; the most serious is rated major. Concomitant use may increase sedative and other adverse effects.

Read the full interaction report
SeverityMajor
LikelihoodLikely
Interactions3
EvidenceC
What do Severity, Likelihood & Evidence mean?
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Interaction report

Beer and Fosphenytoin

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Beer interacts with whole categories of medication. Fosphenytoin falls into 3 of those categories, so it can interact with Beer in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Major).

Major

CNS DEPRESSANTS

1 of 3

Why this applies to Fosphenytoin

Fosphenytoin falls under CNS DEPRESSANTS — the group Beer interacts with.

Concomitant use may increase sedative and other adverse effects.
Concomitant use of alcohol with CNS depressants can increase sedative and other adverse effects, potentially through inhibition of the metabolism of certain CNS depressants.
Severity Major Likelihood Likely Evidence C

Well-controlled human studies have demonstrated the likely existence of this interaction.

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

Here's the practical side of mixing beer with fosphenytoin. This is a seizure medication, and alcohol piles onto the same kind of effects, so together they can leave you feeling more drowsy, dizzy, foggy, or unsteady on your feet than either one alone. That added sedation can sneak up on you and raise your fall risk.

There's also a metabolism wrinkle. Fosphenytoin is converted in your body to phenytoin, which has a narrow safety window, meaning small changes in its blood level can tip you toward side effects or, over time, poorer seizure control. Heavy or regular drinking can shift those levels in ways that are hard to predict. The safest move is to talk with your doctor or pharmacist before drinking any beer while on this medicine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fraser AG. Pharmacokinetic interactions between alcohol and other drugs. Clin Pharmacokinet 1997;33:79-90. PubMed
Major

HEPATOTOXIC DRUGS

2 of 3

Fosphenytoin also falls under HEPATOTOXIC DRUGS.

Concomitant use of alcohol with hepatotoxic drugs may increase the risk of hepatotoxicity.
Concomitant use of excessive amounts of alcohol with potentially hepatotoxic drugs can increase the risk of liver damage.
Severity Major Likelihood Probable Evidence B

Interaction 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..

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

Here's the simple version: both beer and fosphenytoin (Cerebyx) put a workload on your liver. Fosphenytoin is converted in the body into phenytoin, and your liver is the main organ that handles it. Heavy or regular drinking can stress or injure liver cells, and pairing that with this medicine may raise the chance of liver harm. Watch for warning signs like yellowing of the skin or eyes, dark urine, belly pain on the upper right side, unusual tiredness, or nausea.

This concern is mostly about excessive alcohol, not a single light drink, but since fosphenytoin is a serious seizure medicine with a narrow safe range, it's worth caution. Please check with your doctor or pharmacist about whether any alcohol is okay for you, and don't change your medication on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fraser AG. Pharmacokinetic interactions between alcohol and other drugs. Clin Pharmacokinet 1997;33:79-90. PubMed
  2. Thummel, K. E., Slattery, J. T., Ro, H., Chien, J. Y., Nelson, S. D., Lown, K. E., and Watkins, P. B. Ethanol and production of the hepatotoxic metabolite of acetaminophen in healthy adults. Clin Pharmacol Ther 2000;67(6):591-599. PubMed
Major

PHENYTOIN (Dilantin)

3 of 3
Concomitant use may decrease the effectiveness of phenytoin.
Chronic, heavy alcohol use can induce the metabolism of phenytoin, reducing therapeutic effectiveness.
Severity Major Likelihood Probable Evidence C

Interaction 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..

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

Here's the thing about mixing regular heavy drinking with fosphenytoin (Cerebyx): your liver treats alcohol like a wake-up call. Over time, steady drinking can speed up the enzymes that break down fosphenytoin (which your body converts to phenytoin). When the drug clears out faster, your blood levels can drop below where they need to be, and that's a real problem for a seizure medicine. The main worry isn't a side effect, it's losing seizure control because the drug isn't sticking around long enough to do its job.

This applies to chronic, heavy drinking, not an occasional single beer. Phenytoin is a narrow-window medicine, so even modest changes in its level matter. If you drink regularly or want to, please talk it over with your doctor or pharmacist so they can check your levels rather than guessing.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Fraser AG. Pharmacokinetic interactions between alcohol and other drugs. Clin Pharmacokinet 1997;33:79-90. PubMed

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

Beer Also Interacts With Other Medications

Beer has 653 major, 272 moderate known drug interactions in our database — the Fosphenytoin one above is among them. If you take anything else, check it against the full list below.

Major 653 Moderate 272 No known interaction 1,905 (incl. Fosphenytoin)
Taking anything else?

Check Another of Your Medications Against Beer

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

Everything else you take

See Every Supplement That Interacts With Fosphenytoin

This page covers Beer only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fosphenytoin page lists 205 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), Cesium (major) and Ephedra (major).

By severity: 14 major · 172 moderate · 19 minor.

From our pharmacist’s overview on the Fosphenytoin page

“St. John's wort is the entry I would flag first with fosphenytoin (Cerebyx).”

Reviewed by 2 · Jul 18, 2026

Open the Fosphenytoin interaction page

How much people look this up

Where Beer and Fosphenytoin 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 Beer
Top 25%

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

29 days ago today
Medication Fosphenytoin
Steady interest

#2,141 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 Beer

What is Beer?

Beer
  • Social and recreational drinking
  • Relaxation
  • Heart health (popular belief)
  • Bone health (popular belief)
  • Source of antioxidants and B vitamins

Beer is an alcoholic beverage that contains some minerals, B vitamins, and plant compounds from hops and grain, but it is not a health supplement. Any possible benefits come only from light-to-moderate intake, and they are easily outweighed by the well-known harms of alcohol. The safest amount of alcohol for health is none, and beer should be avoided in pregnancy and breastfeeding.

Read the full Beer monograph & all interactions
Medication

About Fosphenytoin Injection

What Is Fosphenytoin Injection Used For?

Brand name: Cerebyx

Fosphenytoin injection is used to treat generalized tonic-clonic status epilepticus (a prolonged, life-threatening seizure emergency) and to prevent or treat seizures that occur during or after brain surgery. It is given by intravenous (IV) or intramuscular (IM) injection in a hospital or clinical setting.

It can also be used short-term as a substitute for oral phenytoin when a patient cannot take medicine by mouth. This use is temporary — as soon as oral phenytoin is possible again, it should replace the injection.

See full Fosphenytoin Injection drug information
Keep checking

Other Drugs & Beer

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

653Major
272Moderate
0Minor
1,904No known interaction
653 Major 272 Moderate 1,904 No interaction
Major

653 interactions

Showing 60 of 653 major interactions — see all 653 on the Beer page.

Moderate

272 interactions

Showing 60 of 272 moderate interactions — see all 272 on the Beer page.

No interaction 1,904 drugs checked — show the list

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

Showing the 60 most looked-up of 1,904 medications checked with no known interaction — see the full Beer list.

See the full Beer interactions page
See every supplement checked against Fosphenytoin, 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
Beer monograph › Uses, safety, and every drug interaction in one place Fosphenytoin supplement interactions › Every supplement checked against Fosphenytoin, ranked by severity Fosphenytoin Injection drug information › The full plain-English guide to this medication 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 Beer and Fosphenytoin Together: Common Questions

Can you take Beer with Fosphenytoin?
This is rated a major interaction, so the combination is best avoided unless your doctor or pharmacist has specifically told you otherwise. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Beer and Fosphenytoin?
Fosphenytoin belongs to more than one drug category, and Beer interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Beer and Fosphenytoin interaction?
We rate it Major. This is a clinically significant combination that is generally best avoided, or used only under the direct supervision of your physician or pharmacist.

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

Still Have a Question About Fosphenytoin and Beer?

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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.