Drug & supplement interaction

Hemp + 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 Hemp 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

Hemp 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 Hemp 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.

Hemp safety at a glance

Hemp overall Use caution Hemp seed foods are generally well tolerated, but concentrated extracts and supplements are less studied.
Pregnancy Use caution Hemp seed foods are likely fine in normal amounts, but concentrated extracts should be avoided due to limited safety data.
Breastfeeding Use caution Food amounts of hemp seed are likely okay, but supplements and extracts are not well studied, so caution is advised.

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

Still wondering about combining Levothyroxine and Hemp? 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. Hemp has documented interactions with 6 drug classes — the most serious being estrogens (moderate), ace inhibitors (aceis) (minor) and anticoagulant/antiplatelet drugs (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

Hemp Does Interact With Other Medications

Hemp has 41 moderate, 897 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 41 Minor 897 No known interaction 1,892 (incl. Levothyroxine)
Taking anything else?

Check Another of Your Medications Against Hemp

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

What to actually watch for

No Interaction Found — But Data Suggests Hemp 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. 5 of them are worth acting on rather than waiting out — marked below.

  • Wheezing / Shortness of breath / Hives Worth acting on Additional detail

    Hemp

    “Orally, there are case reports of allergy to hemp seed, although this is uncommon. A 44-year-old male developed hives during a meal of hemp seed-crusted seafoods. Later, he developed facial swelling, shortness of breath, and problems speaking. Evaluation revealed allergy to a specific protein in hemp seed. He did not react to smoked cannabis.”

    Hemp · Natural Medicines adverse-effect record, reported in allergic rhinitis (hay fever).

    4 sources cited
    1. 101140. Stadtmauer G, Beyer K, Bardina L, Sicherer SH. Anaphylaxis to ingestion of hempseed (Cannabis sativa). J Allergy Clin Immunol. 2003;112(1):216-7. PubMed
    2. 101154. Alkhammash S, Tsui H, Thomson DMP. Cannabis and hemp seed allergy. J Allergy Clin Immunol Pract. 2019;7(7):2429-2430.e1. PubMed
    3. 110288. Clark E, Nilsson U, Samaran Q, Raison-Peyron N. Allergic contact dermatitis from Cannabis sativa (hemp) seed oil. Contact Dermatitis 2022;87(3):292-293.
    4. 101155. Stokes JR, Hartel R, Ford LB, Casale TB. Cannabis (hemp) positive skin tests and respiratory symptoms. Ann Allergy Asthma Immunol. 2000;85(3):238-40. PubMed

    Levothyroxine

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

  • Seizures Worth acting on Additional detail

    Hemp

    “Orally, there is a case report of elevated liver enzymes and hepatitis in a two-year-old boy given hemp extract 2.5 mL, providing 125 mg phytocannabinoid, five to eight times daily for infantile spasms and refractory seizures. The total dose of phytocannabinoids was approximately 60-100 mg/kg daily.”

    Hemp · Natural Medicines adverse-effect record, reported in epilepsy.

    1 source cited
    1. 110287. Singh M, Sehgal M, Yacoub M, et al. Severe liver dysfunction in a toddler receiving nonprescription phytocannabinoid. J Am Pharm Assoc (2003) 2022;62(4):1438-1440. PubMed

    Levothyroxine

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

  • A severe allergic reaction Worth acting on Additional detail

    Hemp

    “Orally, hemp products are generally well tolerated in food amounts. In larger amounts, hemp seed oil seems to be well tolerated.

    Serious Adverse Effects (Rare):

    Orally: Rare cases of anaphylaxis have been reported. Long QT syndrome, torsades de pointes, and syncope have also been reported rarely.”

    Hemp · Natural Medicines adverse-effect record, reported in torsades de pointes.

    Levothyroxine

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

  • A skin rash Additional detail

    Hemp

    Recorded for Hemp in the same Natural Medicines adverse-effect record shown under Wheezing / Shortness of breath / Hives above.

    Levothyroxine

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

Reported for Hemp but not commonly for Levothyroxine: liver problems, an irregular heartbeat, swelling and fainting.

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

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Hemp 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 Hemp 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.

Overlapping uses

What Levothyroxine Is Prescribed For, and What Hemp Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Levothyroxine is a prescription medicine with approved uses on its FDA label. Hemp is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Levothyroxine is prescribed for: 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.

Hemp has been studied for:

  • Constipation studied, not established Hemp has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Hemp for constipation

    Oral hemp seed has only been evaluated in combination with other ingredients; its effect when used alone is unclear.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Levothyroxine on your own; if you are taking Hemp for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Hemp 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 Hemp 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 Hemp 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 Hemp as Part of a Dietary Supplement Product? Check It for Interactions

We hold 720 real supplement products containing Hemp, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Hemp. Even though Hemp 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 Hemp 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 Hemp
Top 25%

#176 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 Hemp reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Hemp 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 Hemp

What is Hemp?

Hemp
  • Plant-based protein source
  • Heart health support
  • Skin and hair health
  • Reducing inflammation
  • General nutrition (omega fatty acids)

Hemp seeds and hemp seed oil are nutritious foods rich in protein, fiber, and healthy omega-3 and omega-6 fatty acids, and they are generally safe for most people as part of the diet. While the nutrition is real, strong human evidence that hemp supplements treat specific medical conditions is limited. Talk with your pharmacist or doctor before using hemp products for a health concern, especially if you are pregnant or breastfeeding.

Cannabis sativa · Cannabaceae · Seeds (hemp hearts), seed oil, protein powder, and sometimes leaves and extracts · Hemp seeds (hearts), hemp seed oil, hemp protein powder, capsules, and food products

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

Hemp: dosing

There is no official standard dose for hemp as a supplement. As a food, people often add a few tablespoons of hemp seeds, oil, or protein powder to meals and snacks.Because products vary widely in strength and form, the best approach is to follow the directions on the product label. They can help you decide whether it is a good fit and what amount may be reasonable for you.

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

Read the full Hemp 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 & Hemp

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

0Major
41Moderate
897Minor
1,891No known interaction
41 Moderate 897 Minor 1,891 No interaction
Moderate

41 interactions

Minor

897 interactions

Showing 60 of 897 minor interactions — see all 897 on the Hemp page.

No interaction 1,891 drugs checked — show the list

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

Showing the 60 most looked-up of 1,891 medications checked with no known interaction — see the full Hemp list.

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

Hemp References

The 12 references that drive our Hemp 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. Kaul N, Kreml R, Austria JA, et al. A comparison of fish oil, flaxseed oil and hempseed oil supplementation on selected parameters of cardiovascular health in healthy volunteers. J Am Coll Nutr 2008;27:51-8. PubMed
  2. Saberivand A, Karimi I, Becker LA, et al. The effects of Cannabis sativa L. seed (hempseed) in the ovariectomized rat model of menopause. Methods Find Exp Clin Pharmacol. 2010;32(7):467-73. PubMed
  3. Girgih AT, Alashi A, He R, Malomo S, Aluko RE. Preventive and treatment effects of a hemp seed (Cannabis sativa L.) meal protein hydrolysate against high blood pressure in spontaneously hypertensive rats. Eur J Nutr. 2014;53(5):1237-46. PubMed
  4. Richard MN, Ganguly R, Steigerwald SN, Al-Khalifa A, Pierce GN. Dietary hempseed reduces platelet aggregation. J Thromb Haemost. 2007;5(2):424-5. PubMed
  5. Stadtmauer G, Beyer K, Bardina L, Sicherer SH. Anaphylaxis to ingestion of hempseed (Cannabis sativa). J Allergy Clin Immunol. 2003;112(1):216-7. PubMed
  6. Del Bo' C, Deon V, Abello F, et al. Eight-week hempseed oil intervention improves the fatty acid composition of erythrocyte phospholipids and the omega-3 index, but does not affect the lipid profile in children and adolescents with primary hyperlipidemia. PubMed
  7. Alkhammash S, Tsui H, Thomson DMP. Cannabis and hemp seed allergy. J Allergy Clin Immunol Pract. 2019;7(7):2429-2430.e1. PubMed
  8. Stokes JR, Hartel R, Ford LB, Casale TB. Cannabis (hemp) positive skin tests and respiratory symptoms. Ann Allergy Asthma Immunol. 2000;85(3):238-40. PubMed
  9. Déléaval M, Burri H, Bakelants E. Harmless herbs? A case report of acquired long QT syndrome and torsades de pointes in a patient taking herbal supplements. HeartRhythm Case Rep 2022;8(5):309-12. PubMed
  10. Singh M, Sehgal M, Yacoub M, et al. Severe liver dysfunction in a toddler receiving nonprescription phytocannabinoid. J Am Pharm Assoc (2003) 2022;62(4):1438-1440. PubMed
  11. Clark E, Nilsson U, Samaran Q, Raison-Peyron N. Allergic contact dermatitis from Cannabis sativa (hemp) seed oil. Contact Dermatitis 2022;87(3):292-293.
  12. Haron MH, Dale O, Martin K, et al. Evaluation of the Herb-Drug Interaction Potential of Commonly Used Botanicals on the US Market with Regard to PXR- and AhR-Mediated Influences on CYP3A4 and CYP1A2. J Diet Suppl 2022. 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 Hemp and Levothyroxine Together: Common Questions

Is it safe to take Hemp with Levothyroxine?
We do not list a known interaction between Hemp 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 Hemp and Levothyroxine have any of the same side effects?
Yes — our sources link each of them separately to 6 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 Hemp 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 Hemp 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.
Are Hemp and Levothyroxine used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Hemp in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.
How was the Hemp and Levothyroxine combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Hemp has documented interactions with 6 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 Hemp interact with any other medications?
Yes. Hemp has 938 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 — Hemp 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

Hemp 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 12 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Hemp?

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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.