Drug & supplement interaction

Solomon's Seal + Levothyroxine

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

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Oct 4, 2026
The bottom line No known interaction

We found no known interaction between Solomon's Seal 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

Solomon's Seal 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 Solomon's Seal 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.

Solomon's Seal safety at a glance

Solomon's Seal overall Use caution Limited safety data exists in people, so use carefully and choose reputable products.
Pregnancy Avoid Safety has not been established, so it is best to avoid use during pregnancy.
Breastfeeding Avoid There is not enough information to consider it safe while breastfeeding.

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

Still wondering about combining Levothyroxine and Solomon's Seal? 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. Solomon's Seal has documented interactions with 3 drug classes — the most serious being antidiabetes drugs (moderate), chlorpropamide (diabinese) (moderate) and insulin (moderate) — 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

Solomon's Seal Does Interact With Other Medications

Solomon's Seal has 86 moderate 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 86 No known interaction 2,744 (incl. Levothyroxine)
Taking anything else?

Check Another of Your Medications Against Solomon's Seal

Covers the 2,830 medications we’ve checked against Solomon's Seal. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Solomon's Seal and Levothyroxine May Share Several of the Same Side Effects

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.

  • Diarrhea / Nausea Additional detail

    Solomon's Seal

    “A thorough evaluation of safety outcomes has not been conducted. Orally, long-term use of Solomon's seal has been reported to cause gastrointestinal irritation. Use of large doses or overdoses may cause nausea, diarrhea, and other gastrointestinal complaints (18).”

    Solomon's Seal · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    “Orally, Solomon's seal may cause gastrointestinal irritation when used long-term. Use of large doses or overdoses may cause nausea, diarrhea, and other gastrointestinal complaints (18).”

    Solomon's Seal · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Levothyroxine

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

Effects for Levothyroxine come from the ADVERSE REACTIONS section of its FDA label; effects for Solomon's Seal 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 — Solomon's Seal Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Solomon's Seal 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 Solomon's Seal 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 Solomon's Seal 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 Solomon's Seal 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 Solomon's Seal 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 Solomon's Seal as Part of a Dietary Supplement Product? Check It for Interactions

We hold 113 real supplement products containing Solomon's Seal, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Solomon's Seal. Even though Solomon's Seal 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 Solomon's Seal 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 Solomon's Seal
Top half

#583 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 Solomon's Seal reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Solomon's Seal 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 Solomon's Seal

What is Solomon's Seal?

Solomon's Seal
  • Joint and muscle discomfort
  • Tendon and ligament injuries
  • Inflammation
  • Digestive complaints
  • Skin and wound care
  • Dry cough and throat irritation

Solomon's Seal is a traditional herb whose root has long been used for joint, tendon, and muscle complaints, but high-quality human studies are largely lacking. There is not enough reliable evidence to confirm it works for any specific condition, so use it cautiously and talk with your pharmacist or doctor first.

Polygonatum multiflorum · Asparagaceae · Rhizome (root) and sometimes the whole plant · Capsules, dried root, teas, tinctures, powders, and topical salves

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

Solomon's Seal: dosing

There is no standardized, scientifically established dose for Solomon's Seal. Products vary widely in strength and form, so amounts on labels are not based on strong clinical research.If you choose to use it, follow the directions on the product label and do not exceed the suggested amount. Because doses are not well studied, it is wise to start low.

From our Solomon's Seal monograph — the full record covers uses, side effects and every documented interaction.

Read the full Solomon's Seal 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 thyroid hormone when your body does not make enough. The oral products (tablets, capsules and oral solution) treat hypothyroidism, which can be present from birth or develop later. They are also used alongside surgery and radioiodine therapy for thyrotropin-dependent well-differentiated thyroid cancer.

Levothyroxine Sodium injection (given intravenously) is used only for myxedema coma, a life-threatening emergency from severe hypothyroidism. Age ranges differ by product. For example, Tirosint capsules are labeled for adults and children 6 years and older.

Most-Reported Side Effects for Levothyroxine

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 26,588 reports
Nausea 22,608 reports
Headache 19,408 reports
Diarrhea 18,758 reports
Dyspnea 16,725 reports
See full Levothyroxine drug information
Keep checking

Other Drugs & Solomon's Seal

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Solomon's Seal page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Solomon's Seal list.

See the full Solomon's Seal interactions page
See every supplement checked against Levothyroxine, ranked by severity
Evidence & sources

Solomon's Seal References

The 2 references that drive our Solomon's Seal 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. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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 Solomon's Seal and Levothyroxine Together: Common Questions

Is it safe to take Solomon's Seal with Levothyroxine?
We do not list a known interaction between Solomon's Seal 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 Solomon's Seal and Levothyroxine have any of the same side effects?
Yes — our sources link each of them separately to 2 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 Solomon's Seal 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 Solomon's Seal 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 Solomon's Seal and Levothyroxine combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Solomon's Seal 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 Solomon's Seal interact with any other medications?
Yes. Solomon's Seal has 86 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 — Solomon's Seal 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

Solomon's Seal 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Solomon's Seal?

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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.