Drug & supplement interaction

Thyroid Extract + Fluconazole

Fluconazole brand names: Diflucan, Diflucan Injection.

Minor Interaction
Medically reviewed by · Updated November 2023
The bottom line Minor

Thyroid Extract has a minor interaction with Fluconazole. Food and medications can interfere with thyroid hormone absorption.

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

Thyroid Extract and Fluconazole

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

Minor

Oral Drugs

Why this applies to Fluconazole

Fluconazole falls under Oral Drugs — the group Thyroid Extract interacts with.

Food and medications can interfere with thyroid hormone absorption. Some foods, particularly those high in fiber or containing certain minerals like calcium or iron, can bind to thyroid hormones and reduce their absorption in the digestive tract. Additionally, taking thyroid medications with certain drugs, like antacids or calcium supplements, can hinder the effectiveness of the thyroid medication, necessitating adjustments in dosage or timing. Prescription thyroid medications, such as Synthroid, are recommended to be taken on an empty stomach, at least 30 minutes before food and other medications, for optimal absorption.
Severity Minor Likelihood Likely Evidence A

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 simple version: this interaction is really about your thyroid extract, not so much about the fluconazole itself. Thyroid hormones (the T4 and T3 in the extract) absorb best on an empty stomach, and other pills taken at the same time can get in the way and lower how much hormone your body picks up.

Fluconazole isn't a prodrug, and it doesn't need your thyroid hormone to work, so your antifungal treatment should stay effective. The main concern is simply timing. If you swallow both together, you may absorb a bit less thyroid hormone. This is rated minor, but an easy fix is to space them out (take your thyroid dose on an empty stomach, then take fluconazole later). Your pharmacist can help you set a schedule.

Contact Dr. Brian directly if you have additional questions on this interaction

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

Thyroid Extract Also Interacts With Other Medications

Thyroid Extract has 3 moderate, 2,018 minor known drug interactions in our database — the Fluconazole one above is one of them. If you take anything else, check it against the full list below.

Moderate 3 Minor 2,018 No known interaction 809 (incl. Fluconazole)
Taking anything else?

Check Another of Your Medications Against Thyroid Extract

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

From our Q&A

Questions About Thyroid Extract or Fluconazole

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Thyroid Extract or Fluconazole, 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 Fluconazole

This page covers Thyroid Extract only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Fluconazole page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Beer (major), Siberian Cocklebur (major), Wine (major) and Adrafinil (moderate).

By severity: 4 major · 54 moderate · 23 minor.

From our pharmacist’s overview on the Fluconazole page

“Fluconazole (Diflucan) treats fungal infections, and I would pair it with supplements carefully. Nearly half of the 81 ingredients with an interaction on file, 38 of them, put extra strain on the liver, which is already busy processing the antifungal.”

Reviewed by 2 · Jul 18, 2026

Open the Fluconazole interaction page

How much people look this up

Where Thyroid Extract and Fluconazole 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 Thyroid Extract
Top half

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

29 days ago today
Medication Fluconazole
Top 25%

#581 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 Thyroid Extract

What is Thyroid Extract?

Thyroid Extract
  • Hypothyroidism (underactive thyroid)
  • Fatigue and low energy
  • Weight management
  • Sluggish metabolism
  • General thyroid support

Thyroid extract supplements are made from dried animal thyroid gland and may contain real thyroid hormones (T3 and T4), but the amounts in over-the-counter products are not standardized and can be unpredictable. Self-treating a thyroid problem with these supplements can be risky, so always work with a doctor or pharmacist and use prescription thyroid medicine when treatment is needed.

Read the full Thyroid Extract monograph & all interactions
Medication

About Fluconazole

What Is Fluconazole Used For?

Brand names: Diflucan, Diflucan Injection

Fluconazole treats infections caused by Candida and Cryptococcus fungi. Diflucan tablets and oral fluconazole tablets and suspension are approved to treat vaginal yeast infections (vaginal candidiasis), thrush in the mouth or throat (oropharyngeal candidiasis), and yeast infections of the esophagus. All forms — tablets, oral suspension, and injection — are used for cryptococcal meningitis (a serious fungal brain infection). In smaller studies, fluconazole has also shown effectiveness against Candida urinary tract infections, peritonitis (infection in the abdomen), and serious systemic (bloodstream and organ) Candida infections.

Fluconazole is also used to prevent candidiasis in people undergoing bone marrow transplants who receive chemotherapy or radiation therapy. Note that vaginal candidiasis is an approved use for the tablets and Diflucan oral products, but not for the injection or oral suspension alone.

See full Fluconazole drug information
Keep checking

Other Drugs & Thyroid Extract

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

0Major
3Moderate
2,018Minor
808No known interaction
3 Moderate 2,018 Minor 808 No interaction
Moderate

3 interactions

Minor

2,018 interactions

Showing 60 of 2,018 minor interactions — see all 2,018 on the Thyroid Extract page.

No interaction 808 drugs checked — show the list

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

Showing the 60 most looked-up of 808 medications checked with no known interaction — see the full Thyroid Extract list.

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

Can you take Thyroid Extract with Fluconazole?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Thyroid Extract and Fluconazole interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Fluconazole and Thyroid Extract?

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.