Propionyl-l-carnitine + Liotrix
Liotrix brand names: Euthroid 3, Euthroid 1/2, Euthroid 1.
Propionyl-l-carnitine has a moderate interaction with Liotrix. Theoretically, acetyl-L-carnitine might decrease the effectiveness of thyroid hormone replacement.
Read the full interaction reportPropionyl-l-carnitine and Liotrix
Here is the interaction we found between these two, with the evidence behind it.
THYROID HORMONE
Why this applies to Liotrix
Liotrix falls under THYROID HORMONE — the group Propionyl-l-carnitine interacts with.
L-carnitine appears to act as a peripheral thyroid hormone antagonist by inhibiting entry of thyroid hormone into the nucleus of cells. Taking L-carnitine also seems to diminish some of the symptoms of hyperthyroidism. It is unclear if such an interaction would occur with propionyl-L-carnitine.
Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
Here's the gist for liotrix (a mix of T4 and T3 thyroid hormone). Carnitine seems to act as a mild thyroid hormone blocker by keeping thyroid hormone from getting into the part of your cells where it works. So in theory, taking enough carnitine could nudge your thyroid replacement to work a little less well, which might bring back symptoms like fatigue, feeling cold, constipation, or weight creep.
That said, this is mostly theoretical, and the research is on L-carnitine, not specifically the propionyl form you're asking about, so we honestly don't know if it does the same thing. I wouldn't panic, but I also wouldn't add a carnitine supplement without a quick chat with your pharmacist or doctor. If you do start it, checking your thyroid levels (TSH) afterward is a smart move.
- Benvenga S, Ruggeri RM, Russo A, et al. Usefulness of L-carnitine, a naturally occurring peripheral antagonist of thyroid hormone action, in iatrogenic hyperthyroidism: a randomized, double-blind, placebo-controlled clinical trial. J Clin Endocrinol Meta
- 12761 Benvenga S, Amato A, Calvani M, Trimarchi F. Effects of carnitine on thyroid hormone action. Ann N Y Acad Sci 2004;1033:158-67. PubMed
What These Ratings Mean
Every interaction above is graded three ways — here’s the key to each label.
Clinically significant. Avoid the combination, or use only under close professional supervision.
Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.
Generally not serious. Be aware of it and mention it to your pharmacist.
- LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
- ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
- PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
- UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
- AHigh-quality meta-analysis (quantitative systematic review).
- BCase-control study.
- CConsensus.
- DAnecdotal evidence.
These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.
Propionyl-l-carnitine Also Interacts With Other Medications
Propionyl-l-carnitine has 18 moderate known drug interactions in our database — the Liotrix one above is one of them. If you take anything else, check it against the full list below.
Check Another of Your Medications Against Propionyl-l-carnitine
We haven’t checked that one against Propionyl-l-carnitine yet — ask our pharmacists directly.
Covers the 2,830 medications we’ve checked against Propionyl-l-carnitine. Pick one to open its full report.
See Every Supplement That Interacts With Liotrix
This page covers Propionyl-l-carnitine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Liotrix page lists 38 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 · 26 moderate · 10 minor.
From our pharmacist’s overview on the Liotrix page
“Liotrix (Euthroid) combines both thyroid hormones, and since steady hormone levels are the entire point of treatment, this list deserves a slow, serious read. Most entries fall into two camps: twenty-one ingredients act on the hormone itself, some boosting it and others blunting it, while another seventeen change how well the dose is a…”
Reviewed by 2 · Jul 18, 2026
Taking Propionyl-l-carnitine as Part of a Dietary Supplement Product? Check It for Interactions
We hold 57 real supplement products containing Propionyl-l-carnitine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Propionyl-l-carnitine. Your product may carry other ingredients that interact with Liotrix too, on top of Propionyl-l-carnitine — and those would not show on this page. Find your product and we’ll check every ingredient on its label:
Where Propionyl-l-carnitine and Liotrix 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.
#1,247 of 1,452 supplements looked up here in the last 7 days
#2,256 of 2,830 medications looked up here in the last 7 days
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.
About Propionyl-l-carnitine
What is Propionyl-l-carnitine?
- Peripheral artery disease and leg pain
- Heart and circulation support
- Energy and exercise performance
- Erectile dysfunction
- Diabetic nerve pain
Propionyl-l-carnitine is a form of the amino acid derivative carnitine that the body uses to help turn fat into energy, and it is studied mostly for circulation problems like peripheral artery disease. Some evidence suggests it may help walking distance in people with poor leg circulation, but results are mixed and it is not a substitute for standard medical care. Talk to a pharmacist or doctor before using it, especially if you have a medical condition or take other medicines.
About Liotrix
What Is Liotrix Used For?
Brand names: Euthroid 3, Euthroid 1/2, Euthroid 1
-
Liotrix is used to treat hypothyroidism (a condition that results when the thyroid gland does not produce enough thyroid hormone). Symptoms of hypothyroidism include lack of energy, depression, constipation, weight gain, hair loss, dry skin, dry coarse hair, muscle cramps, decreased concentration, aches and pains, swelling of the legs, and increased sensitivity to cold. When taken correctly, liotrix can reverse these symptoms. Liotrix is also used to treat goiter (enlarged thyroid gland). This medication is also used to test for hyperthyroidism (a condition where the thyroid gland produces too much thyroid hormone). Liotrix is in a class of medications called thyroid agents. It works by supplying the thyroid hormones normally produced by the body.
Other Drugs & Propionyl-l-carnitine
Browse every other medication we’ve checked against Propionyl-l-carnitine — both the ones with a known interaction and the ones without. Select any drug for the full detail.
No drugs match “”.
18 interactions
- Levothyroxine ›
- Conjugated Estrogens ›
- Testosterone Undecanoate ›
- Levothyroxine Sodium ›
- Warfarin Sodium ›
- Desiccated Thyroid Extract ›
- Desiccated Thyroid Extract (prescription Drug) ›
- Menotropins ›
- Acenocoumarol ›
- Dextrothyroxine ›
- Human Chorionic Gonadotropin (hcg) ›
- Liothyronine ›
- Ospemifene ›
- Thyroglobulin ›
- Thyroid Hormone ›
- Warfarin ›
- Levothyroxine, Liothyronine ›
- Liotrix, T4/t3 ›
No interaction 2,811 drugs checked — show the list
We also checked Propionyl-l-carnitine against these medications and found no known interaction in our sources. Open any page to confirm.
- Apixaban ›
- Amlodipine ›
- Methylphenidate ›
- Sertraline ›
- Testosterone ›
- Losartan Potassium ›
- Metoprolol ›
- Aspirin ›
- Ivermectin ›
- Rivaroxaban ›
- Rosuvastatin ›
- Escitalopram ›
- Acetaminophen ›
- Tadalafil ›
- Clopidogrel ›
- Atorvastatin ›
- Docusate ›
- Valacyclovir ›
- Abemaciclib ›
- Hydroxyurea ›
- Methamphetamine ›
- Ibuprofen ›
- Sumatriptan ›
- Semaglutide ›
- Tirzepatide ›
- Prednisone ›
- Propranolol ›
- Bupropion ›
- Metformin ›
- Lisdexamfetamine ›
- Amoxicillin ›
- Lisinopril ›
- Acyclovir ›
- Bendamustine ›
- Amitriptyline ›
- Doxycycline ›
- Methotrexate ›
- Lamotrigine ›
- Fluoxetine ›
- Amphetamine ›
- Acetaminophen, Codeine ›
- Gabapentin ›
- Pregabalin ›
- Azithromycin ›
- Dextroamphetamine ›
- Isotretinoin ›
- Clonazepam ›
- Omeprazole ›
- Methylene Blue ›
- Quetiapine ›
- Amlodipine Besylate ›
- Duloxetine ›
- Letrozole ›
- Buspirone ›
- Citalopram ›
- Naproxen ›
- Ciprofloxacin ›
- Bisoprolol ›
- Acetaminophen, Oxycodone ›
- Dapsone ›
Showing the 60 most looked-up of 2,811 medications checked with no known interaction — see the full Propionyl-l-carnitine list.
Sources & How We Checked
Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference for vitamins, herbs and supplements — the basis for our interaction data.
- MedlinePlus, U.S. National Library of Medicine — NIH consumer drug information, used for the medication overviews.
- NIH Dietary Supplement Label Database (DSLD) — Official supplement product labels.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.
Parts of this content are provided by the Therapeutic Research Center, LLC.
DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.
© 2021 Therapeutic Research Center, LLC
Taking Propionyl-l-carnitine and Liotrix Together: Common Questions
Can you take Propionyl-l-carnitine with Liotrix?
How serious is the Propionyl-l-carnitine and Liotrix interaction?
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