Drug & supplement interaction

Dhea + Fulvestrant

Fulvestrant brand name: Faslodex.

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

Dhea has a moderate interaction with Fulvestrant. Theoretically, DHEA might interfere with the anti-estrogen effects of fulvestrant.

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

Dhea and Fulvestrant

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

Moderate

FULVESTRANT (Faslodex)

Theoretically, DHEA might interfere with the anti-estrogen effects of fulvestrant.
DHEA is a potent estrogen agonist. Some research shows that it can overcome the estrogen receptor antagonist action of fulvestrant in estrogen-receptor positive cancer cells.
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 DHEA and fulvestrant (Faslodex). Your body can turn DHEA into estrogen, and fulvestrant works by blocking and breaking down estrogen receptors to slow hormone-driven breast cancer. So in theory, raising your estrogen activity with DHEA could push against the very thing fulvestrant is trying to do, possibly making the treatment less effective.

I want to be honest about the evidence here: this comes from lab and cell studies, not from people, so it's theoretical. Still, because fulvestrant is a cancer therapy, I wouldn't take chances. Please don't start or stop anything on your own. Talk with your oncologist or pharmacist before using DHEA, especially with a hormone-sensitive cancer.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Calhoun KE, Pommier RF, Muller P, et al. Dehydroepiandrosterone sulfate causes proliferation of estrogen receptor-positive breast cancer cells despite treatment with fulvestrant. Arch Surg 2003;138:879-83.. PubMed
  2. Morris KT, Toth-Fejel S, Schmidt J, et al. High dehydroepiandrosterone-sulfate predicts breast cancer progression during new aromatase inhibitor therapy and stimulates breast cancer cell growth in tissue culture: a renewed role for adrenalectomy. Surgery 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

Dhea Also Interacts With Other Medications

Dhea has 767 moderate, 8 minor known drug interactions in our database — the Fulvestrant one above is one of them. If you take anything else, check it against the full list below.

Moderate 767 Minor 8 No known interaction 2,055 (incl. Fulvestrant)
Taking anything else?

Check Another of Your Medications Against Dhea

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

Everything else you take

See Every Supplement That Interacts With Fulvestrant

This page covers Dhea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fulvestrant page lists 1 supplement it has a documented interaction with, worst first, each one explained.

By severity: 1 moderate.

Open the Fulvestrant interaction page

One more smart check

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

We hold 945 real supplement products containing Dhea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Dhea. Your product may carry other ingredients that interact with Fulvestrant too, on top of Dhea — 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 Dhea and Fulvestrant 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 Dhea
Top 25%

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

29 days ago today
Medication Fulvestrant
Steady interest

#2,463 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 Dhea

What is Dhea?

Dhea
  • Anti-aging and low DHEA levels
  • Mood and depression
  • Vaginal dryness and sexual health
  • Fertility support
  • Muscle mass and athletic performance
  • Adrenal insufficiency

DHEA is a natural hormone that the body makes and that declines with age, and it is sold as a supplement claiming many benefits. The evidence is mixed and limited for most uses, and because it acts as a hormone it can cause real side effects. Talk to a pharmacist or doctor before using it, especially if you have a hormone-sensitive condition.

Read the full Dhea monograph & all interactions
Medication

About Fulvestrant Injection

What Is Fulvestrant Injection Used For?

Brand name: Faslodex

Fulvestrant injection treats hormone receptor (HR)-positive advanced breast cancer in postmenopausal women. It can be used alone for women who have not yet had endocrine (hormone-blocking) therapy, or for women whose cancer has grown despite endocrine therapy.

It is also used in combination with other medicines — palbociclib, abemaciclib, or ribociclib — for HR-positive, HER2-negative advanced or metastatic breast cancer in women whose disease has progressed after endocrine therapy. Fulvestrant injection combined with ribociclib may also be used as an initial hormone-based treatment in this setting.

See full Fulvestrant Injection drug information
Keep checking

Other Drugs & Dhea

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

0Major
767Moderate
8Minor
2,054No known interaction
767 Moderate 8 Minor 2,054 No interaction
Moderate

767 interactions

Showing 60 of 767 moderate interactions — see all 767 on the Dhea page.

Minor

8 interactions

No interaction 2,054 drugs checked — show the list

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

Showing the 60 most looked-up of 2,054 medications checked with no known interaction — see the full Dhea list.

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

Can you take Dhea with Fulvestrant?
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 Dhea and Fulvestrant 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 Fulvestrant and Dhea?

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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.