Medication interaction hub

What Supplements Interact with Levothyroxine?

Levothyroxine brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, and others. Every interaction below applies to the brands too.

50 Interactions 2 Major 39 Moderate 9 Minor
Curated & coded by · Clinical Pharmacist · Updated September 22, 2026

Drug–supplement interaction data sourced from Natural Medicines Pro, the licensed clinical database from TRC Healthcare / Therapeutic Research, with additional analysis by the HelloPharmacist Pharmacist Team. Our sources · Editorial policy

What is this page for?

One answer, for one medication: what supplements and herbal products interact with Levothyroxine? Every vitamin, herb, and supplement ingredient we’ve checked against it is on this page, ranked by severity, each linking to the full report for that exact pair.

This page covers supplement interactions only — to check Levothyroxine against your other medications, use the drug–drug interaction checker. Educational information from our licensed clinical databases, not medical advice. Our editorial policy

HelloPharmacist Bottom Line
Our Pharmacist Explains
What is this? The interaction data in the HelloPharmacist supplement database is licensed from Natural Medicines Pro by TRC Healthcare (Therapeutic Research). HelloPharmacist pharmacists often add our own analysis and context on top of that licensed data — such as this Bottom Line summary and the notes on individual interaction pages — and any such commentary is noted as ours.

Levothyroxine replaces a hormone your body measures in tiny amounts, so small shifts in its blood level show up in how you feel, and I treat this list with genuine care. Nearly everything on it does one of two things: blocks the pill from being absorbed in the gut, the way everyday minerals like calcium do by binding it into complexes, or pushes thyroid hormone activity itself up or down. Activated charcoal and tiratricol carry the two highest ratings, and tiratricol worries me most because it is a thyroid hormone in its own right, so combining them stacks effect on effect.

For the absorption group, spacing doses well apart usually solves the problem, with specifics in each entry below. The entries that mimic or blunt thyroid hormone cannot be timed around, so raise those with your pharmacist before starting one. Two of the 50 ingredients here rate major, 39 moderate, and 9 minor, and on a drug this dose-sensitive, even the moderates deserve a careful read.

— , Clinical Pharmacist · July 18, 2026

Major 2 Moderate 39 Minor 9 No known interaction 1,402

This box checks one ingredient at a time (like turmeric or magnesium). Taking a supplement product with a whole label of ingredients? Search the product instead — we check every ingredient on it ↓

Most Viewed Ingredient Interactions

Levothyroxine: Top Interactions at a Glance

The Levothyroxine supplement & herbal interactions people checked most in the last 24 hours, colored by severity. Tap any ingredient to open the full report for that pair.

Showing the 12 highest-ranked of 50 interacting ingredients — plus 1,402 more checked with no known interaction. See the complete ranked list.

Start here

The Most-Checked Levothyroxine Combinations Today

The Levothyroxine + supplement pages people viewed most in the last 24 hours (resets at midnight). Open any card for the full report.

Moderate Likelihood Probable Iron + Levothyroxinei

Iron might decrease levothyroxine levels by reducing its absorption.

Read the full interaction Moderate Likelihood Probable Ashwagandha + Levothyroxinei

Ashwagandha might increase the effects and adverse effects of thyroid hormone.

Read the full interaction Moderate Likelihood Probable L-carnitine + Levothyroxinei

Theoretically, L-carnitine might decrease the effectiveness of thyroid hormone replacement.

Read the full interaction Moderate Likelihood Possible Soy + Levothyroxinei

Soy products might reduce the absorption of levothyroxine in some patients.

Read the full interaction Moderate Likelihood Possible Coffee + Levothyroxinei

Coffee can reduce the absorption of levothyroxine.

Read the full interaction Moderate Likelihood Possible Alpha-lipoic Acid + Levothyroxinei

Theoretically, alpha-lipoic acid might decrease the effects of thyroid hormone drugs.

Read the full interaction
The complete list

Every Supplement Checked Against Levothyroxine

All 1,452 ingredients in our database, ranked by severity — 50 with a Levothyroxine interaction on file and 1,402 with none found. Filter by severity or search any ingredient; hover the for what each ingredient is.

Looking for an interaction with a specific supplement product? Search products instead ↓

Straight answers

Can You Take It With Levothyroxine?

One-line answers, one card per combination — scroll through today’s 20 and tap any card for the full report. A different set rotates in daily until every combination has had its turn.

Can you take Iron with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Iron might decrease levothyroxine levels by reducing its absorption.

Full Iron + Levothyroxine answer

Can you take Ashwagandha with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Ashwagandha might increase the effects and adverse effects of thyroid hormone.

Full Ashwagandha + Levothyroxine answer

Can you take L-carnitine with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, L-carnitine might decrease the effectiveness of thyroid hormone replacement.

Full L-carnitine + Levothyroxine answer

Can you take Soy with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Soy products might reduce the absorption of levothyroxine in some patients.

Full Soy + Levothyroxine answer

Can you take Coffee with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Coffee can reduce the absorption of levothyroxine.

Full Coffee + Levothyroxine answer

Can you take Activated Charcoal with Levothyroxine?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Activated charcoal reduces systemic exposure to many drugs, including those that undergo enterohepatic recirculation, regardless of the rout...

Full Activated Charcoal + Levothyroxine answer

Can you take Tiratricol with Levothyroxine?

Major Use real caution — this is a major-rated interaction, generally best avoided or used only under close supervision. Concomitant use of tiratricol with thyroid hormones may have additive effects.

Full Tiratricol + Levothyroxine answer

Can you take Acetyl-l-carnitine with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, acetyl-L-carnitine might decrease the effectiveness of thyroid hormone replacement.

Full Acetyl-l-carnitine + Levothyroxine answer

Can you take Bugleweed with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, bugleweed may alter thyroid function.

Full Bugleweed + Levothyroxine answer

Can you take Calcium with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Calcium seems to reduce the absorption and effectiveness of levothyroxine.

Full Calcium + Levothyroxine answer

Can you take Chromium with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Chromium might bind levothyroxine in the intestinal tract and decrease levothyroxine absorption.

Full Chromium + Levothyroxine answer

Can you take Coffee Charcoal with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Coffee charcoal can reduce the absorption of orally administered drugs and should be separated from oral drug administration by at least two...

Full Coffee Charcoal + Levothyroxine answer

Can you take Dolomite with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. The calcium in dolomite seems to reduce the absorption and effectiveness of levothyroxine.

Full Dolomite + Levothyroxine answer

Can you take European Mandrake with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, concurrent use might increase absorption of some drugs because of inhibited gastrointestinal (GI) motility caused by European...

Full European Mandrake + Levothyroxine answer

Can you take Glucomannan with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, glucomannan may decrease absorption of drugs taken orally.

Full Glucomannan + Levothyroxine answer

Can you take Guggul with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, guggul might increase the risk for adverse effects when taken with thyroid hormone therapy.

Full Guggul + Levothyroxine answer

Can you take Niacin with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, niacin might antagonize the therapeutic effects of thyroid hormones.

Full Niacin + Levothyroxine answer

Can you take Tyrosine with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, tyrosine might have additive effects with thyroid hormone medications.

Full Tyrosine + Levothyroxine answer

Can you take Vitamin C with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Vitamin C can increase levothyroxine absorption.

Full Vitamin C + Levothyroxine answer

Can you take Alpha-lipoic Acid with Levothyroxine?

Moderate Possibly, but carefully — this moderate-rated combination may need monitoring, a dose adjustment, or separated timing. Theoretically, alpha-lipoic acid might decrease the effects of thyroid hormone drugs.

Full Alpha-lipoic Acid + Levothyroxine answer
Read the list like a pharmacist

What Severity, Likelihood & Evidence Mean

Severity — How Serious It Can Be

  • Major. Clinically significant; generally best avoided, or used only under direct professional supervision.
  • Moderate. May need monitoring, a dose adjustment, or separating the times you take each one.
  • Minor. Generally not clinically significant, but still worth noting and mentioning to your pharmacist.
  • No known interaction. Checked against our sources with nothing documented — not the same as proven safety.

Likelihood — How Well It’s Documented

  • Likely. Well-controlled human studies have demonstrated the likely existence of this interaction
  • Probable. 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.
  • Possible. 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
  • Unlikely. Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans.

Where This Data Comes From

  • Interaction records are evidence-graded and sourced from the Natural Medicines database (TRC Healthcare), the same reference used by pharmacists and hospitals.
  • Each entry links to a full report with the clinical detail, likelihood, evidence level, and citations for that exact combination.
  • Content is reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

How Does Our Interaction Checker Work?

Behind every verdict on this page is a category system. Our source database doesn’t document supplement interactions drug-by-drug — it documents them against groups of medications that behave the same way (for example, “drugs processed by the CYP3A4 liver enzyme” or “blood-thinning medications”).

So the check works in three steps: (1) Levothyroxine is classified into the pharmacology categories it belongs to, (2) every supplement interaction documented against any of those categories is inherited by Levothyroxine, and (3) each ingredient keeps its own severity, likelihood, and evidence grades from the underlying record. That’s why one supplement can carry several records for one drug — it may interact through more than one category.

Levothyroxine sits in 3 interaction categories. Open any one to see what the group means:

Thyroid Hormone 21 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

21 of the supplement ingredients on this page reach Levothyroxine through this category.

Oral Drugs 17 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

17 of the supplement ingredients on this page reach Levothyroxine through this category.

Levothyroxine (Synthroid, Others) 13 ingredients

A pharmacology grouping from our source database: medications in this group share a property that certain supplements are known to interact with, so an interaction documented for the group applies to every drug in it.

13 of the supplement ingredients on this page reach Levothyroxine through this category.

About Levothyroxine

Levothyroxine is a hormone used to replace thyroid hormone and treat hypothyroidism and thyroid cancer.

Generic name: Levothyroxine  ·  Brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, Levo-T, Eltroxin, Estre, Levothyroxine, Novothyrox, Levolet, Ermez, Thyquidity, Tirosint-Sol.

See the full Levothyroxine drug information
Check a real product

Take a Supplement Product? Check the Whole Bottle Against Levothyroxine

Most supplements are combination products — and the interaction may come from an ingredient you didn’t buy it for. Search any product below (or scan its label) and we’ll check every ingredient on it against Levothyroxine.

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Pharmacist Counseling Corner

Levothyroxine & Supplements: Common Questions

What supplements interact with Levothyroxine?
More than you might expect — 50 in total, though they are far from equal: 2 are rated major, 39 moderate, and 9 minor. The ranked list on this page puts the ones that genuinely matter first, and every entry opens a full report on that exact pair. The highest-ranked right now: Activated Charcoal, Tiratricol, Acetyl-l-carnitine.
Which Levothyroxine supplement interactions are the most serious?
Focus on the major group: Activated Charcoal and Tiratricol. A major rating means the combination can be clinically significant, not that harm is guaranteed — but it's exactly the kind of thing to run past your pharmacist before your next dose, not after. Jump to the ranked list.
Can I take vitamins or supplements while on Levothyroxine?
Usually yes — most people on Levothyroxine can take most supplements. The catch is the exceptions, and they aren't always the exotic ones (St. John's Wort trips up more prescriptions than almost anything sold next to it). Look up each ingredient you actually take in the list above, and treat "no known interaction" as a green-ish light, not a guarantee. Try the label scanner or the interaction checker.
Do brands like Euthyrox have the same supplement interactions as Levothyroxine?
Yes — Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl and other brands all contain Levothyroxine, so everything on this page applies to them equally. Interactions belong to the active drug, never to the brand on the box; the same is true of generics.
Where do these interaction ratings come from?
Every rating comes from the Natural Medicines database — the same evidence-graded reference pharmacists and hospitals use — and each interaction carries three separate grades: severity (how bad it can be), likelihood (how well it's documented in studies and case reports), and an evidence level. Our pharmacists review the content; we never let an AI decide an interaction. See how to read the ratings and our editorial policy.
What about Levothyroxine and my other medications?
This page covers Levothyroxine against supplements and herbal ingredients. Checking Levothyroxine against your other prescription or OTC medications is a different tool — our drug interaction checker covers that side. Head to the drug–drug interaction checker, or read the full Levothyroxine drug information.

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

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Sourcing

Where This Data Comes From — and Why You Can Trust It

🧪 Licensed clinical database

Every interaction verdict on this page comes from Natural Medicines Pro (TRC Healthcare / Therapeutic Research) — the same evidence-graded reference used by pharmacists and hospitals. We license this data directly; we do not scrape it, and no AI invents an interaction.

🧑‍⚕️ Pharmacist review

This page is curated and coded by , Clinical Pharmacist, with additional analysis by the HelloPharmacist Pharmacist Team. Editorial commentary is ours; the licensed interaction records are shown as sourced.

🔄 Kept current

Our interaction database refreshes on a weekly cycle, and this page re-checks the live database every time it’s rebuilt — what you see reflects the database as of September 22, 2026.

🔍 Full transparency

How every dataset on this site is sourced, licensed, and updated is documented publicly: our data sources · editorial policy · how we use AI.

Educational information, not medical advice. An interaction being on file does not mean it will happen to you — and absence of one is not proof of safety. Never start or stop a medication or supplement without talking to your pharmacist or doctor.