Drug & supplement interaction

Sulforaphane + Levothyroxine Sodium

Levothyroxine Sodium brand names: Tirosint-Sol, Thyquidity, Ermez.

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 Sulforaphane and Levothyroxine Sodium 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 Sodium 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

Sulforaphane and Levothyroxine Sodium

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 Sodium and Sulforaphane 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.

Sulforaphane safety at a glance

Sulforaphane overall Use caution Sulforaphane from food is considered safe, but concentrated supplements are less studied for long-term use.
Pregnancy Likely Safe When used orally in amounts found in foods. There is insufficient reliable information available about the safety of sulforaphane in medicinal amounts. Read the full pregnancy detail
Breastfeeding Likely Safe When used orally in amounts found in foods. There is insufficient reliable information available about the safety of sulforaphane in medicinal amounts. 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 Sodium and Sulforaphane? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Levothyroxine Sodium

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine Sodium is filed under 3 classifications — including thyroid hormone, oral drugs. Sulforaphane has documented interactions with 3 drug classes — the most serious being cytochrome p450 1a2 (cyp1a2) substrates (moderate), cytochrome p450 2e1 (cyp2e1) substrates (moderate) and cytochrome p450 3a4 (cyp3a4) substrates (moderate) — and none of Levothyroxine Sodium’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

Sulforaphane Does Interact With Other Medications

Sulforaphane has 722 moderate known drug interactions in our database — Levothyroxine Sodium isn’t one of them. If you take anything else, check it against the full list below.

Moderate 722 No known interaction 2,108 (incl. Levothyroxine Sodium)
Taking anything else?

Check Another of Your Medications Against Sulforaphane

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

What to actually watch for

No Interaction Found — But Data Suggests Sulforaphane and Levothyroxine Sodium 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. One of them is worth acting on rather than waiting out — marked below.

  • Seizures Worth acting on Additional detail

    Sulforaphane

    “Orally, sulforaphane has been reported to cause headache in one clinical study. In another clinical trial, insomnia and irritability were reported. Sulforaphane has also been associated with two cases of seizure in males with autism. In one case, a patient with a recent history of seizure experienced a seizure after taking sulforaphane for 3 weeks.”

    Sulforaphane · Natural Medicines adverse-effect record, reported in autism spectrum disorder.

    3 sources cited
    1. 104537. Momtazmanesh S, Amirimoghaddam-Yazdi Z, Moghaddam HS, Mohammadi MR, Akhondzadeh S. Sulforaphane as an adjunctive treatment for irritability in children with autism spectrum disorder: A randomized, double-blind, placebo-controlled clinical trial. Psychiatr PubMed
    2. 108131. Zimmerman AW, Singh K, Connors SL, et al. Randomized controlled trial of sulforaphane and metabolite discovery in children with Autism Spectrum Disorder. Mol Autism 2021;12(1):38.
    3. 95267. Singh K, Connors SL, Macklin EA, et al. Sulforaphane treatment of autism spectrum disorder (ASD). Proc Natl Acad Sci U S A. 2014;111(43):15550-5. PubMed

    Levothyroxine Sodium

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

  • Mood changes or irritability / Trouble sleeping / Headache reported in 6.2% of FDA reports for Levothyroxine Sodium Additional detail

    Sulforaphane

    Recorded for Sulforaphane in the same Natural Medicines adverse-effect record shown under Seizures above.

    Levothyroxine Sodium

    Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine Sodium, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Vomiting Additional detail

    Sulforaphane

    “Orally, sulforaphane and sulforaphane-rich extracts can cause bowel discomfort, stomach upset, heartburn, and vomiting. A specific stabilized form of sulforaphane (Cavamax W6) caused mild stomach upset in 60% of subjects in a small study. However, in some clinical studies, the gastrointestinal side effects reported with sulforaphane did not occur more frequently than with placebo.”

    Sulforaphane · Natural Medicines adverse-effect record, reported in dyspepsia.

    6 sources cited
    1. 95251. Cipolla BG, Mandron E, Lefort JM, et al. Effect of sulforaphane in men with biochemical recurrence after radical prostatectomy. Cancer Prev Res (Phila). 2015;8(8):712-9. PubMed
    2. 95252. Fahey JW, Wade KL, Wehage SL, et al. Stabilized sulforaphane for clinical use: Phytochemical delivery efficiency. Mol Nutr Food Res. 2017 Apr;61(4). PubMed
    3. 95260. Alumkal JJ, Slottke R, Schwartzman J, et al. A phase II study of sulforaphane-rich broccoli sprout extracts in men with recurrent prostate cancer. Invest New Drugs. 2015;33(2):480-9. PubMed
    4. 95265. Heber D, Li Z, Garcia-Lloret M, et al. Sulforaphane-rich broccoli sprout extract attenuates nasal allergic response to diesel exhaust particles. Food Funct. 2014;5(1):35-41. PubMed
    5. 95267. Singh K, Connors SL, Macklin EA, et al. Sulforaphane treatment of autism spectrum disorder (ASD). Proc Natl Acad Sci U S A. 2014;111(43):15550-5. PubMed
    6. 95268. Wise RA, Holbrook JT, Criner G, et al. Lack of effect of oral sulforaphane administration on Nrf2 expression in COPD: A randomized, double-blind, placebo controlled trial. PLoS One. 2016;11(11):e0163716. PubMed

    Levothyroxine Sodium

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

Reported for Sulforaphane but not commonly for Levothyroxine Sodium: weight gain, stomach upset and heartburn.

Effects for Levothyroxine Sodium come from the ADVERSE REACTIONS section of its FDA label; effects for Sulforaphane come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 312,551 voluntary FDA FAERS reports for Levothyroxine Sodium that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Sulforaphane in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally in amounts found in foods. There is insufficient reliable information available about the safety of sulforaphane in medicinal amounts.

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

How to take them

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

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

Everything else you take

See Every Supplement That Interacts With Levothyroxine Sodium

This page covers Sulforaphane only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine Sodium 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).

Open the Levothyroxine Sodium interaction page

One more smart check

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

We hold 167 real supplement products containing Sulforaphane, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Sulforaphane. Even though Sulforaphane itself has no known interaction with Levothyroxine Sodium, 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 Sulforaphane and Levothyroxine Sodium 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 Sulforaphane
Top half

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

29 days ago today
Medication Levothyroxine Sodium
Top 5%

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

What is Sulforaphane?

  • Antioxidant support
  • General cellular health
  • Detoxification support
  • Inflammation
  • Skin and aging concerns

Sulforaphane is a natural compound found in broccoli and other cruciferous vegetables that has shown promising antioxidant and anti-inflammatory effects in lab studies, but strong human evidence for most specific health claims is still limited. It is generally well tolerated as part of a vegetable-rich diet, but if you take a concentrated supplement, talk to your pharmacist or doctor first.

Brassicaceae · Derived from cruciferous vegetables, especially broccoli sprouts and seeds · Capsules, tablets, powders, broccoli sprout extracts, and 'broccoli seed extract' supplements often standardized to glucoraphanin

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

Sulforaphane: dosing

There is no official, standardized dose of sulforaphane. Supplements vary widely in how they are made and how much active compound they actually deliver. Many products are labeled by glucoraphanin content or by 'active sulforaphane,' and the amount of usable sulforaphane can differ depending on whether the enzyme myrosinase is present.Because of this variability, the best approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full Sulforaphane monograph & all interactions
Medication

About Levothyroxine Sodium

Most-Reported Side Effects for Levothyroxine Sodium

From FAERS, the FDA’s public side-effect reporting system (312,551 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 26,585 reports
Nausea 22,605 reports
Headache 19,408 reports
Diarrhea 18,759 reports
Dyspnea 16,717 reports
Keep checking

Other Drugs & Sulforaphane

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

0Major
722Moderate
0Minor
2,107No known interaction
722 Moderate 2,107 No interaction
Moderate

722 interactions

Showing 60 of 722 moderate interactions — see all 722 on the Sulforaphane page.

No interaction 2,107 drugs checked — show the list

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

Showing the 60 most looked-up of 2,107 medications checked with no known interaction — see the full Sulforaphane list.

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

Sulforaphane References

The 16 references that drive our Sulforaphane 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. Park EJ, Pezzuto JM. Botanicals in cancer chemoprevention. Cancer Metastasis Rev 2002;21:231-55. PubMed
  2. Barcelo S, Mace K, Pfeifer AM, Chipman JK. Production of DNA strand breaks by N-nitrosodimethylamine and 2-amino-3-methylimidazo[4,5-f]quinoline in THLE cells expressing human CYP isoenzymes and inhibition by sulforaphane. Mutat Res 1998;402:111-20. PubMed
  3. Cipolla BG, Mandron E, Lefort JM, et al. Effect of sulforaphane in men with biochemical recurrence after radical prostatectomy. Cancer Prev Res (Phila). 2015;8(8):712-9. PubMed
  4. Fahey JW, Wade KL, Wehage SL, et al. Stabilized sulforaphane for clinical use: Phytochemical delivery efficiency. Mol Nutr Food Res. 2017 Apr;61(4). PubMed
  5. Alumkal JJ, Slottke R, Schwartzman J, et al. A phase II study of sulforaphane-rich broccoli sprout extracts in men with recurrent prostate cancer. Invest New Drugs. 2015;33(2):480-9. PubMed
  6. Heber D, Li Z, Garcia-Lloret M, et al. Sulforaphane-rich broccoli sprout extract attenuates nasal allergic response to diesel exhaust particles. Food Funct. 2014;5(1):35-41. PubMed
  7. Singh K, Connors SL, Macklin EA, et al. Sulforaphane treatment of autism spectrum disorder (ASD). Proc Natl Acad Sci U S A. 2014;111(43):15550-5. PubMed
  8. Wise RA, Holbrook JT, Criner G, et al. Lack of effect of oral sulforaphane administration on Nrf2 expression in COPD: A randomized, double-blind, placebo controlled trial. PLoS One. 2016;11(11):e0163716. PubMed
  9. Bent S, Lawton B, Warren T, et al. Identification of urinary metabolites that correlate with clinical improvements in children with autism treated with sulforaphane from broccoli. Mol Autism. 2018;9:35. PubMed
  10. Momtazmanesh S, Amirimoghaddam-Yazdi Z, Moghaddam HS, Mohammadi MR, Akhondzadeh S. Sulforaphane as an adjunctive treatment for irritability in children with autism spectrum disorder: A randomized, double-blind, placebo-controlled clinical trial. Psychiatr PubMed
  11. Fimognari C, Lenzi M, Hrelia P. Interaction of the isothiocyanate sulforaphane with drug disposition and metabolism: pharmacological and toxicological implications. Curr Drug Metab. 2008;9(7):668-78. PubMed
  12. Chinnappan SM, George A, Evans M, Anthony J. Efficacy of Labisia pumila and Eurycoma longifolia standardised extracts on hot flushes, quality of life, hormone and lipid profile of peri-menopausal and menopausal women: a randomised, placebo-controlled stud
  13. Mahéo K, Morel F, Langouët S, et al. Inhibition of cytochromes P-450 and induction of glutathione S-transferases by sulforaphane in primary human and rat hepatocytes. Cancer Res. 1997;57(17):3649-52.
  14. Yoxall V, Kentish P, Coldham N, Kuhnert N, Sauer MJ, Ioannides C. Modulation of hepatic cytochromes P450 and phase II enzymes by dietary doses of sulforaphane in rats: Implications for its chemopreventive activity. Int J Cancer. 2005;117(3):356-62. PubMed
  15. Zimmerman AW, Singh K, Connors SL, et al. Randomized controlled trial of sulforaphane and metabolite discovery in children with Autism Spectrum Disorder. Mol Autism 2021;12(1):38.

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 Sulforaphane and Levothyroxine Sodium Together: Common Questions

Is it safe to take Sulforaphane with Levothyroxine Sodium?
We do not list a known interaction between Sulforaphane and Levothyroxine Sodium. 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 Sulforaphane and Levothyroxine Sodium have any of the same side effects?
Yes — our sources link each of them separately to 5 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 Sulforaphane and Levothyroxine Sodium at the same time of day?
At least one FDA label for a product containing Levothyroxine Sodium 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 Sodium on its own and move Sulforaphane 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 Sulforaphane and Levothyroxine Sodium combination checked?
Interactions in our licensed database are recorded against drug classes. Levothyroxine Sodium is filed under 3 classifications, and Sulforaphane has documented interactions with 3 drug classes — none of Levothyroxine Sodium'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 Sulforaphane interact with any other medications?
Yes. Sulforaphane has 722 documented drug interactions in our database — Levothyroxine Sodium 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 Sodium interact with any supplements?
Yes. Levothyroxine Sodium has documented interactions with 50 supplements in our database — Sulforaphane is not one of them. The Levothyroxine Sodium 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

Sulforaphane monograph Uses, safety profile, and every drug interaction in one place Levothyroxine Sodium supplement interactions Every supplement checked against Levothyroxine Sodium, 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 16 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Levothyroxine Sodium and Sulforaphane?

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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.