Drug & supplement interaction

Adrafinil + Tamoxifen Citrate

Tamoxifen Citrate brand names: Nolvadex, Soltamox.

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

Tamoxifen Citrate falls into 2 drug categories that Adrafinil can interact with; the most serious is rated moderate. Theoretically, adrafinil might increase the levels and clinical effects of CYP2C9 substrates.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Adrafinil and Tamoxifen Citrate

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Adrafinil interacts with whole categories of medication. Tamoxifen Citrate falls into 2 of those categories, so it can interact with Adrafinil in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

1 of 2

Why this applies to Tamoxifen Citrate

Tamoxifen Citrate falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Adrafinil interacts with.

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 situation with these two. Your liver uses an enzyme called CYP2C9 to help process tamoxifen, and adrafinil (which your body turns into modafinil) may lower the activity of that enzyme. If it slows down, tamoxifen could clear a bit more slowly and build up in your body, which in theory could mean stronger effects and a higher chance of side effects like hot flashes, leg swelling, mood changes, or blood clots.

I want to be honest, though: this is a theoretical concern based only on lab studies, not real patients, so we don't actually know how much it matters in practice. Because tamoxifen is such an important cancer medicine, please loop in your oncologist or pharmacist before adding adrafinil so they can weigh it for you.

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

2 of 2

Tamoxifen Citrate 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 thing to keep in mind with this pairing. Adrafinil turns into modafinil in your body, and modafinil can act as a mild speed-up signal for a liver enzyme called CYP3A4. Tamoxifen partly relies on that same enzyme. So in theory, adrafinil could nudge your body to clear tamoxifen a little faster, which might lower the amount working in your system.

For a breast cancer medicine you're counting on to do an important job, even a small drop in levels is worth taking seriously. The good news is that this concern is theoretical, based on how the drugs behave on paper rather than real cases. Still, since adrafinil is unregulated and hard on the liver, please run it by your oncologist or pharmacist before combining the two.

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.

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 Tamoxifen Citrate 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. Tamoxifen Citrate)
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 Tamoxifen Citrate

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 Tamoxifen Citrate, 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 Tamoxifen Citrate

This page covers Adrafinil only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tamoxifen Citrate page lists 210 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 11 major · 166 moderate · 33 minor.

From our pharmacist’s overview on the Tamoxifen Citrate page

“Tamoxifen (Nolvadex, Soltamox) often stands between a breast cancer patient and a recurrence, so the stakes on this page run higher than usual. Eleven of the 210 supplements and herbs on file carry a major rating, and those eleven deserve your attention ahead of everything else.”

Reviewed by 2 · Jul 18, 2026

Open the Tamoxifen Citrate 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 Tamoxifen Citrate 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 Tamoxifen Citrate 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

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

29 days ago today
Medication Tamoxifen Citrate
Top 10%

#163 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 Tamoxifen

What Is Tamoxifen Used For?

Brand names: Nolvadex, Soltamox

Tamoxifen is used to treat metastatic breast cancer (breast cancer that has spread) in both women and men, and as adjuvant (after-surgery) therapy for early-stage breast cancer in women. It also reduces the occurrence of cancer in the opposite breast when used as adjuvant therapy.

In women with ductal carcinoma in situ (DCIS) — a very early, non-invasive form of breast cancer — tamoxifen is used after breast surgery and radiation to reduce the risk of developing invasive breast cancer. It is also approved to reduce the incidence of breast cancer in women who are at high risk but have not yet been diagnosed. Soltamox (oral solution) is specifically indicated for all of these uses in adult patients.

See full Tamoxifen 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 Tamoxifen Citrate, 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 Tamoxifen Citrate supplement interactions › Every supplement checked against Tamoxifen Citrate, ranked by severity Tamoxifen 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 Tamoxifen Citrate Together: Common Questions

Can you take Adrafinil with Tamoxifen Citrate?
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 2 interactions listed for Adrafinil and Tamoxifen Citrate?
Tamoxifen Citrate 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 Tamoxifen Citrate 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 Tamoxifen Citrate and Adrafinil?

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.