Drug & supplement interaction

Hordenine + Levothyroxine

Levothyroxine brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, and others.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Hordenine and Levothyroxine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the label for Levothyroxine states a food rule worth keeping to, and the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Hordenine and Levothyroxine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Levothyroxine and Hordenine in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Hordenine safety at a glance

Hordenine overall Use caution Human safety data is very limited, and it acts as a stimulant.
Pregnancy Avoid No safety data; avoid use during pregnancy.
Breastfeeding Avoid No safety data; avoid while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Levothyroxine and Hordenine? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Levothyroxine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine is filed under 3 classifications — including thyroid hormone, oral drugs. Hordenine has documented interactions with 3 drug classes — the most serious being monoamine oxidase inhibitors (maois) (moderate), stimulant drugs (moderate) and cytochrome p450 2d6 (cyp2d6) substrates (minor) — and none of Levothyroxine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Hordenine Does Interact With Other Medications

Hordenine has 180 moderate, 149 minor known drug interactions in our database — Levothyroxine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 180 Minor 149 No known interaction 2,501 (incl. Levothyroxine)
Taking anything else?

Check Another of Your Medications Against Hordenine

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

What to actually watch for

No Interaction Found — But Data Suggests Hordenine and Levothyroxine May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • A fast or pounding heartbeat Additional detail

    Hordenine

    “No clinical studies have evaluated the safety of hordenine in humans. However, hordenine is structurally similar to the stimulants N-methyltyramine and synephrine, which are found in bitter orange. Theoretically, hordenine may cause stimulant-related side effects similar to these compounds, including tachycardia and hypertension.”

    Hordenine · Natural Medicines adverse-effect record, reported in hypertension.

    1 source cited
    1. 29888. Nelson BC, Putzbach K, Sharpless KE, Sander LC. Mass spectrometric determination of the predominant adrenergic protoalkaloids in bitter orange (Citrus aurantium). J Agric Food Chem 2007;55(24):9769-75. PubMed

    “Hordenine is structurally similar to the stimulants N-methyltyramine and synephrine, which are found in bitter orange. Theoretically, hordenine may cause stimulant-related side effects similar to these compounds, including tachycardia and hypertension. However, this has not been assessed or reported in humans.”

    Hordenine · Natural Medicines adverse-effect record, reported in hypertension.

    1 source cited
    1. 29888. Nelson BC, Putzbach K, Sharpless KE, Sander LC. Mass spectrometric determination of the predominant adrenergic protoalkaloids in bitter orange (Citrus aurantium). J Agric Food Chem 2007;55(24):9769-75. PubMed

    Levothyroxine

    Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›

Reported for Hordenine but not commonly for Levothyroxine: raised blood pressure.

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Hordenine come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

How to take them

Some Levothyroxine Products Have a Food Rule — Hordenine Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Hordenine included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Levothyroxine on its own and move Hordenine to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Levothyroxine products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Hordenine or Levothyroxine

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

This page covers Hordenine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine page lists 50 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Tiratricol (major), Acetyl-l-carnitine (moderate), Alpha-lipoic Acid (moderate) and Ascophyllum Nodosum (moderate).

By severity: 2 major · 39 moderate · 9 minor.

From our pharmacist’s overview on the Levothyroxine page

“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,…”

Reviewed by 2 · Jul 18, 2026

Open the Levothyroxine interaction page

One more smart check

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

We hold 339 real supplement products containing Hordenine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Hordenine. Even though Hordenine itself has no known interaction with Levothyroxine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Hordenine and Levothyroxine 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 Hordenine
Top 25%

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

29 days ago today
Medication Levothyroxine
Top 10

#2 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Hordenine reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Hordenine and Levothyroxine records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Hordenine

What is Hordenine?

Hordenine
  • Energy and stimulation
  • Athletic and workout performance
  • Weight loss/fat burning
  • Focus and mood
  • Appetite control

Hordenine is a natural alkaloid found in barley and some cacti that is marketed as a stimulant for energy, focus, and fat loss, but solid human evidence for these benefits is lacking. Its safety in people has not been well studied, so caution is warranted, and it should be avoided in pregnancy, breastfeeding, and by people with heart conditions.

Alkaloid isolated from plants such as barley sprouts and certain cacti · Capsules, tablets, powders (often in pre-workout and 'fat burner' blends)

An interaction check asks whether these two react with each other — it does not ask whether Hordenine is a good idea for someone in your situation. Here is what our Hordenine record says about it on its own.

Hordenine: dosing

There is no established, well-studied dose for hordenine. The amounts found in supplements vary widely, and they have not been tested for safety or effectiveness in proper human trials.If you choose to use a product containing hordenine, follow the label instructions and do not exceed them. Be aware that it is often mixed with caffeine and other stimulants, so the total stimulant load may be higher than it appears.

From our Hordenine monograph — the full record covers uses, side effects and every documented interaction.

Read the full Hordenine monograph & all interactions
Medication

About Levothyroxine

What Is Levothyroxine Used For?

Brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, Levo-T, Eltroxin, Estre, Levothyroxine, Novothyrox, Levolet

Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain.

It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

See full Levothyroxine drug information
Keep checking

Other Drugs & Hordenine

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

0Major
180Moderate
149Minor
2,500No known interaction
180 Moderate 149 Minor 2,500 No interaction
Moderate

180 interactions

Showing 60 of 180 moderate interactions — see all 180 on the Hordenine page.

Minor

149 interactions

Showing 60 of 149 minor interactions — see all 149 on the Hordenine page.

No interaction 2,500 drugs checked — show the list

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

Showing the 60 most looked-up of 2,500 medications checked with no known interaction — see the full Hordenine list.

See the full Hordenine interactions page
See every supplement checked against Levothyroxine, ranked by severity
Evidence & sources

Hordenine References

The 3 references that drive our Hordenine monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Barwell CJ, Basma AN, Lafi MA, Leake LD. Deamination of hordenine by monoamine oxidase and its action on vasa deferentia of the rat. J Pharm Pharmacol 1989;41(6):421-3. PubMed
  2. Nelson BC, Putzbach K, Sharpless KE, Sander LC. Mass spectrometric determination of the predominant adrenergic protoalkaloids in bitter orange (Citrus aurantium). J Agric Food Chem 2007;55(24):9769-75. PubMed
  3. Liu Y, Santillo MF. Cytochrome P450 2D6 and 3A4 enzyme inhibition by amine stimulants in dietary supplements. Drug Test Anal. 2016;8(3-4):307-10. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Hordenine and Levothyroxine Together: Common Questions

Is it safe to take Hordenine with Levothyroxine?
We do not list a known interaction between Hordenine and Levothyroxine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Hordenine and Levothyroxine have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Should I take Hordenine and Levothyroxine at the same time of day?
At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Levothyroxine on its own and move Hordenine to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Hordenine and Levothyroxine combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Hordenine has documented interactions with 3 drug classes — none of Levothyroxine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Hordenine interact with any other medications?
Yes. Hordenine has 329 documented drug interactions in our database — Levothyroxine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Levothyroxine interact with any supplements?
Yes. Levothyroxine has documented interactions with 50 supplements in our database — Hordenine is not one of them. The Levothyroxine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Hordenine monograph Uses, safety profile, and every drug interaction in one place Levothyroxine drug information The full plain-English guide to this medication Levothyroxine supplement interactions Every supplement checked against Levothyroxine, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Hordenine?

Our pharmacists answer your medication & supplement questions — free.

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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.