Drug & supplement interaction

Vegetarian Diet + 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 Vegetarian Diet 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 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

Vegetarian Diet 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 Vegetarian Diet in our sources. This does not guarantee that the combination is completely free of risk — research on Vegetarian Diet alongside specific medications may be limited.

Worth understanding: our licensed dataset holds no drug-interaction record for Vegetarian Diet at all — not against Levothyroxine, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

Vegetarian Diet is an eating pattern rather than something you take. Ask your pharmacist or doctor before changing how you eat while on a prescribed medicine: some medicines are dosed around meals, and a change in diet can change how they work. 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.

Vegetarian Diet safety at a glance

Vegetarian Diet overall Generally safe A well-planned vegetarian diet is generally safe and healthy for most people.
Pregnancy Likely Safe When used appropriately. A position statement from the Academy of Nutrition and Dietetics indicates that a nutritionally adequate vegetarian diet is appropriate... Read the full pregnancy detail
Breastfeeding Likely Safe When used appropriately. A position statement from the Academy of Nutrition and Dietetics indicates that a nutritionally adequate vegetarian diet is appropriate... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Levothyroxine and Vegetarian Diet? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Vegetarian Diet 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 following Vegetarian Diet while taking the medicine can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Bone thinning Worth acting on Additional detail

    Vegetarian Diet

    “Consuming a vegetarian diet can increase the risk for certain nutritional deficiencies due to reduced intake and/or reduced absorption:

    Iron from meat (heme iron) is more bioavailable than iron from plant-derived foods (nonheme iron). Additionally, meat and fish enhance the absorption of nonheme iron.”

    Vegetarian Diet · Natural Medicines adverse-effect record, reported in ariboflavinosis.

    6 sources cited
    1. 99801. Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington (DC): National Academies Press (
    2. 98059. Foster M, Herulah UN, Prasad A, Petocz P, Samman S. Zinc Status of Vegetarians during Pregnancy: A Systematic Review of Observational Studies and Meta-Analysis of Zinc Intake. Nutrients. 2015 Jun 5;7(6):4512-25. PubMed
    3. 109259. Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116(12):1970-1980. PubMed
    4. 98063. Ho-Pham LT, Nguyen ND, Nguyen TV. Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. Am J Clin Nutr. 2009;90(4):943-50. PubMed
    5. 103643. Iguacel I, Miguel-Berges ML, Gómez-Bruton A, Moreno LA, Julián C. Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis. Nutr Rev. 2019;77(1):1-18. PubMed
    6. 98074. Majchrzak D, Singer I, Männer M, et al. B-vitamin status and concentrations of homocysteine in Austrian omnivores, vegetarians and vegans. Ann Nutr Metab. 2006;50(6):485-91. PubMed

    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 Vegetarian Diet 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.

Special populations

Vegetarian Diet in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used appropriately. A position statement from the Academy of Nutrition and Dietetics indicates that a nutritionally adequate vegetarian diet is appropriate during pregnancy and lactation. Following a vegetarian diet when pregnant or lactating should not pose a risk to the child as long as nutritional needs are met. Nutrients of concern may include omega-3 fatty acids, iron, zinc, calcium, vitamin D, and vitamin B12. Additionally, one small observational study has found that consuming a vegetarian diet during pregnancy is not associated with lower cognitive function, as measured by intelligence quotient (IQ), in the child at 6-7 years of age. Although some observational research has found an association between consuming a vegetarian diet during pregnancy and an increased risk for low birth weight or small for gestational age (SGA), most research has not accounted for diet variability or adherence or controlled for nutritional status or body mass index. When specific vegetarian diets are examined, only a vegan diet, not a lacto-ovo-vegetarian diet, has been associated with an increased risk of SGA or low birth weight.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Levothyroxine Is Prescribed For, and What Vegetarian Diet 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. Vegetarian Diet is an eating pattern: 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.

Vegetarian Diet has been studied for:

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

    Vegetarian Diet for depression

    It is unclear if following a vegetarian diet is beneficial for the prevention or treatment of depression.

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

    Vegetarian Diet for cancer

    It is unclear if following a vegetarian diet is beneficial for preventing various forms of cancer.

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 Vegetarian Diet for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Vegetarian Diet 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 Vegetarian Diet 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 Vegetarian Diet 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

How much people look this up

Where Vegetarian Diet 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 Vegetarian Diet
Steady interest

#1,076 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 Vegetarian Diet reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Vegetarian Diet 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 .
Eating pattern

About Vegetarian Diet

What is Vegetarian Diet?

  • Heart health
  • Weight management
  • Blood sugar control
  • Lowering cholesterol
  • Ethical or environmental reasons
  • General wellness

A vegetarian diet emphasizes plant foods and avoids meat, and when well-planned it is linked with lower risks of heart disease, high blood pressure, and type 2 diabetes. It can be very healthy but needs attention to certain nutrients like vitamin B12, iron, and protein. Talk with a doctor or dietitian before making major dietary changes, especially if you are pregnant, nursing, or have a health condition.

Whole-food eating pattern (no specific product form)

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

Vegetarian Diet: dosing

There is no "dose" for a vegetarian diet. Instead, the goal is a balanced, varied eating pattern built around vegetables, fruits, whole grains, beans and lentils, nuts, seeds, and (if included) dairy and eggs.Many vegetarians, especially vegans, benefit from a vitamin B12 supplement or B12-fortified foods. Some also need iron, vitamin D, calcium, or omega-3 supplements depending on their individual needs and lab results.

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

Read the full Vegetarian Diet 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 & Vegetarian Diet

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Vegetarian Diet list.

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

Vegetarian Diet References

The 11 references that drive our Vegetarian Diet 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. Foster M, Herulah UN, Prasad A, Petocz P, Samman S. Zinc Status of Vegetarians during Pregnancy: A Systematic Review of Observational Studies and Meta-Analysis of Zinc Intake. Nutrients. 2015 Jun 5;7(6):4512-25. PubMed
  2. Ho-Pham LT, Nguyen ND, Nguyen TV. Effect of vegetarian diets on bone mineral density: a Bayesian meta-analysis. Am J Clin Nutr. 2009;90(4):943-50. PubMed
  3. Majchrzak D, Singer I, Männer M, et al. B-vitamin status and concentrations of homocysteine in Austrian omnivores, vegetarians and vegans. Ann Nutr Metab. 2006;50(6):485-91. PubMed
  4. Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington (DC): National Academies Press (
  5. Crozier SR, Godfrey KM, Calder PC, et al. Vegetarian Diet during Pregnancy Is Not Associated with Poorer Cognitive Performance in Children at Age 6-7 Years. Nutrients. 2019;11(12):3029. PubMed
  6. Iguacel I, Miguel-Berges ML, Gómez-Bruton A, Moreno LA, Julián C. Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis. Nutr Rev. 2019;77(1):1-18. PubMed
  7. Tan C, Zhao Y, Wang S. Is a vegetarian diet safe to follow during pregnancy? A systematic review and meta-analysis of observational studies. Crit Rev Food Sci Nutr. 2019;59(16):2586-2596. PubMed
  8. Yisahak SF, Hinkle SN, Mumford SL, et al. Vegetarian diets during pregnancy, and maternal and neonatal outcomes. Int J Epidemiol 2021;50(1):165-178. PubMed
  9. Avnon T, Paz Dubinsky E, Lavie I, Ben-Mayor Bashi T, Anbar R, Yogev Y. The impact of a vegan diet on pregnancy outcomes. J Perinatol 2021;41(5):1129-1133. PubMed
  10. Kesary Y, Avital K, Hiersch L. Maternal plant-based diet during gestation and pregnancy outcomes. Arch Gynecol Obstet 2020;302(4):887-898. PubMed
  11. Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116(12):1970-1980. 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

Following Vegetarian Diet While Taking Levothyroxine: Common Questions

Is it safe to follow Vegetarian Diet while taking Levothyroxine?
We do not list a known interaction between Vegetarian Diet 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 Vegetarian Diet 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.
Are Vegetarian Diet 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 Vegetarian Diet in each. That is a conversation for your prescriber, especially if Levothyroxine is being adjusted to a target.
Does Levothyroxine interact with any supplements?
Yes. Levothyroxine has documented interactions with 50 supplements in our database — Vegetarian Diet 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

Vegetarian Diet 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 11 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine and Vegetarian Diet?

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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.