Drug & supplement interaction

Adrafinil + Warfarin Sodium

Warfarin Sodium brand names: Coumadin, Panwarfin, Sofarin.

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

Warfarin Sodium falls into 5 drug categories that Adrafinil can interact with; the most serious is rated moderate. Theoretically, adrafinil might increase the levels and clinical effects of CYP2C19 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions5
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Adrafinil and Warfarin Sodium

These two interact in 5 distinct ways. Each one is explained separately below.

Why Are There 5 Interactions?

Adrafinil interacts with whole categories of medication. Warfarin Sodium falls into 5 of those categories, so it can interact with Adrafinil in 5 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES

1 of 5

Why this applies to Warfarin Sodium

Warfarin Sodium falls under CYTOCHROME P450 2C19 (CYP2C19) SUBSTRATES — the group Adrafinil interacts with.

Theoretically, adrafinil might increase the levels and clinical effects of CYP2C19 substrates.
Adrafinil is a precursor to the stimulant prescription drug modafinil. Modafinil has been shown to inhibit CYP2C19 activity in vitro.
Severity Moderate Likelihood Possible Evidence D

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 warfarin (Coumadin). Adrafinil turns into modafinil in your body, and modafinil can slow down a liver enzyme called CYP2C19. Warfarin is partly cleared by that same enzyme, so in theory combining the two could let warfarin build up a bit and thin your blood more than intended.

Warfarin is a narrow therapeutic index drug, meaning even small shifts matter. Too much can raise your bleeding risk, think easy bruising, nosebleeds, bleeding gums, or blood in your urine or stool. To be clear, this concern is theoretical and based on lab data, not confirmed in people. Still, please don't start adrafinil without checking with your doctor or pharmacist first, and if you do, your INR should be watched closely.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Urban AE, Cubala WJ. The role of eugeroics in the treatment of affective disorders. Psychiatr Pol. 2020;54(1):21-33. PubMed
  2. Kumar R. Approved and investigational uses of modafinil: an evidence-based review. Drugs. 2008;68(13):1803-39. PubMed
  3. Provigil (modafinil) [package insert]. North Wales, PA: Teva Pharmaceuticals USA, Inc. Published: January 2015. Accessed on: Nov 11, 2022.
Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

2 of 5

Warfarin Sodium also falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES.

Theoretically, adrafinil might reduce the levels and clinical effects of CYP1A2 substrates.
Adrafinil is a precursor to the stimulant prescription drug modafinil. Modafinil has been shown to weakly induce CYP1A2 activity in vitro.
Severity Moderate Likelihood Possible Evidence D

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 for warfarin and adrafinil. Once your liver turns adrafinil into modafinil, that modafinil may slightly speed up an enzyme called CYP1A2, one of the pathways that helps clear warfarin. In theory, that could lower your warfarin levels a touch and make your blood a little less thin than your dose intends, which could raise your clot risk.

I want to be honest with you, though: this is a theoretical concern based only on lab data, not real-world reports, so the effect is likely small. But warfarin is a narrow-therapeutic-index drug, meaning even minor shifts can throw off your INR. If you're considering adrafinil, please loop in your doctor or pharmacist first so they can watch your INR closely.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Urban AE, Cubala WJ. The role of eugeroics in the treatment of affective disorders. Psychiatr Pol. 2020;54(1):21-33. PubMed
  2. Kumar R. Approved and investigational uses of modafinil: an evidence-based review. Drugs. 2008;68(13):1803-39. PubMed
  3. Provigil (modafinil) [package insert]. North Wales, PA: Teva Pharmaceuticals USA, Inc. Published: January 2015. Accessed on: Nov 11, 2022.
Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

3 of 5

Warfarin Sodium also falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES.

Theoretically, adrafinil might increase the levels and clinical effects of CYP2C9 substrates.
Adrafinil is a precursor to the stimulant prescription drug modafinil. Modafinil has been shown to reduce CYP2C9 expression in vitro.
Severity Moderate Likelihood Possible Evidence D

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 concern with pairing adrafinil and warfarin. Your liver turns adrafinil into modafinil, and lab studies hint that modafinil may slow down an enzyme called CYP2C9. That same enzyme is one of the main ways your body clears warfarin. If it gets blocked, warfarin could build up and thin your blood more than intended.

Why this matters: warfarin has a very narrow safety window, so even small shifts can tip you toward bleeding (think easy bruising, nosebleeds, pink or dark urine, or bleeding gums). I'll be honest, this interaction is theoretical and based on lab data, not real patient reports, so don't panic. But warfarin isn't a drug to take chances with. Please check with your doctor or pharmacist before combining them, and keep up with your INR testing.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Urban AE, Cubala WJ. The role of eugeroics in the treatment of affective disorders. Psychiatr Pol. 2020;54(1):21-33. PubMed
  2. Kumar R. Approved and investigational uses of modafinil: an evidence-based review. Drugs. 2008;68(13):1803-39. PubMed
Moderate

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

4 of 5

Warfarin Sodium also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, adrafanil might reduce levels and clinical effects of CYP3A4 substrates.
Adrafinil is a precursor to the stimulant prescription drug modafinil. Modafinil has been shown to weakly induce CYP3A4 activity.
Severity Moderate Likelihood Possible Evidence D

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 for warfarin. Once your liver turns adrafinil into modafinil, that modafinil can mildly speed up an enzyme called CYP3A4, which is one of the pathways your body uses to clear warfarin. In theory, that could nudge your warfarin levels down a little, meaning your blood might not be thinned as much as your dose intends.

Why this matters: warfarin is a narrow-therapeutic-index drug, so even small shifts can change your INR and, at worst, raise your risk of clotting. To be honest, this interaction is only theoretical and the effect is considered weak, so don't panic. Still, please loop in your doctor or pharmacist before combining them, and keep up with your regular INR checks so any change gets caught early.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Urban AE, Cubala WJ. The role of eugeroics in the treatment of affective disorders. Psychiatr Pol. 2020;54(1):21-33. PubMed
  2. Provigil (modafinil) [package insert]. North Wales, PA: Teva Pharmaceuticals USA, Inc. Published: January 2015. Accessed on: Nov 11, 2022.
Moderate

WARFARIN (Coumadin)

5 of 5
Theoretically, adrafinil might alter the effects and adverse effects of warfarin.
Adrafinil is a precursor to the stimulant prescription drug modafinil. Although pharmacokinetic research shows that modafinil does not alter levels of warfarin, this study was limited to a single dose. Experts recommend monitoring international normalized ratio (INR) in patients who are taking warfarin and initiating treatment with modafinil.
Severity Moderate Likelihood Possible Evidence D

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 honest picture: this is a theoretical concern, not something that's been clearly proven. Adrafinil turns into modafinil in your body, and a small study showed modafinil didn't change warfarin levels. But that study only looked at a single dose, so experts play it safe and recommend keeping an eye on things.

Why the caution? Warfarin is a narrow-therapeutic-index drug, meaning even small shifts can matter. If your warfarin effect drifts too high, you risk easy bruising, nosebleeds, or more serious bleeding. If it drifts too low, you're at risk for clots. The smart move is simply to tell your doctor before adding adrafinil so they can check your INR more closely for a while. Please don't change your warfarin dose on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Provigil (modafinil) [package insert]. North Wales, PA: Teva Pharmaceuticals USA, Inc. Published: January 2015. Accessed on: Nov 11, 2022.

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

Adrafinil Also Interacts With Other Medications

Adrafinil has 1 major, 1,055 moderate known drug interactions in our database — the Warfarin Sodium one above is among them. If you take anything else, check it against the full list below.

Major 1 Moderate 1,055 No known interaction 1,774 (incl. Warfarin Sodium)
Taking anything else?

Check Another of Your Medications Against Adrafinil

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

From our Q&A

Questions About Adrafinil or Warfarin 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 Adrafinil or Warfarin 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 Warfarin Sodium

This page covers Adrafinil only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Warfarin Sodium page lists 361 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Alfalfa (major), American Ginseng (major), Beer (major) and Cannabis (major).

Open the Warfarin Sodium interaction page

One more smart check

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

We hold 7 real supplement products containing Adrafinil, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Adrafinil. Your product may carry other ingredients that interact with Warfarin Sodium too, on top of Adrafinil — 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 Adrafinil and Warfarin 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 Adrafinil
Top half

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

29 days ago today
Medication Warfarin Sodium
Top 1%

#21 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 Adrafinil

What is Adrafinil?

Adrafinil
  • Wakefulness and alertness
  • Fatigue
  • Focus and concentration
  • Cognitive enhancement (nootropic)
  • Daytime sleepiness

Adrafinil is a synthetic compound that the body converts into modafinil, a prescription wakefulness-promoting drug. It is sometimes sold as a nootropic supplement, but it is unregulated, carries real risks (especially to the liver), and is banned in some sports and countries. Talk with a doctor or pharmacist before using it.

Read the full Adrafinil monograph & all interactions
Medication

About Warfarin

What Is Warfarin Used For?

Brand names: Coumadin, Panwarfin, Sofarin

Warfarin sodium tablets and Jantoven tablets are both used to prevent and treat venous thrombosis (blood clots in the veins) and pulmonary embolism (a clot in the lungs). They are also used to prevent clot-related complications in people with atrial fibrillation (an irregular heart rhythm) or who have had a heart valve replaced.

In people who have had a heart attack, warfarin is used to reduce the risk of death, another heart attack, stroke, or other clotting events. It does not dissolve an existing clot, but it helps prevent the clot from growing and stops new dangerous clots from forming.

See full Warfarin drug information
Keep checking

Other Drugs & Adrafinil

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

1Major
1,055Moderate
0Minor
1,773No known interaction
1 Major 1,055 Moderate 1,773 No interaction
Major

1 interaction

Moderate

1,055 interactions

Showing 60 of 1,055 moderate interactions — see all 1,055 on the Adrafinil page.

No interaction 1,773 drugs checked — show the list

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

Showing the 60 most looked-up of 1,773 medications checked with no known interaction — see the full Adrafinil list.

See the full Adrafinil interactions page
See every supplement checked against Warfarin 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
Adrafinil monograph › Uses, safety, and every drug interaction in one place Warfarin Sodium supplement interactions › Every supplement checked against Warfarin Sodium, ranked by severity Warfarin 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 Adrafinil and Warfarin Sodium Together: Common Questions

Can you take Adrafinil with Warfarin 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.
Why are there 5 interactions listed for Adrafinil and Warfarin Sodium?
Warfarin Sodium belongs to more than one drug category, and Adrafinil 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 Adrafinil and Warfarin 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 Warfarin Sodium and Adrafinil?

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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.