Levothyroxine and Mounjaro

[Hapyjackie]

Has anyone taking Levothyroxine had any issues taking the weight loss injection mounjaro?

[helvella Administrator]

Manufacturer's own information:

Can people take Mounjaro® (tirzepatide) with levothyroxine?

Levothyroxine is not contraindicated with the use of tirzepatide; however, tirzepatide delays gastric emptying and thereby has the potential to impact the absorption of concomitantly administered oral medications like levothyroxine.

See important safety information, including boxed warning, in the attached prescribing information.

Use With Levothyroxine

Levothyroxine is not contraindicated with the use of tirzepatide.1

Tirzepatide delays gastric emptying and thereby has the potential to impact the absorption of concomitantly administered oral medications. The impact of tirzepatide on gastric emptying was greatest after a single dose of 5 mg and diminished after subsequent doses.1

Monitor patients on oral medications dependent on threshold concentrations for efficacy and those with a narrow therapeutic index (NTI) when concomitantly administered with tirzepatide.1

The Food and Drug Administration (FDA) has concluded that levothyroxine is a NTI drug.2-4

Eli Lilly and company does not provide specific treatment recommendations. We strongly encourage patients to go to their healthcare provider for treatment advice because they know their patient's medical history the best.

The prescribing information for levothyroxine includes a warning for worsening of diabetic control: Therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control after starting, changing, or discontinuing thyroid hormone therapy.4

Enclosed Prescribing Information

MOUNJARO® (tirzepatide) injection, for subcutaneous use, Lilly

References

1Mounjaro [package insert]. Indianapolis, IN: Eli Lilly and Company; 2023.

2US Food and Drug Administration (FDA). Draft Guidance on Levothyroxine Sodium. Updated December 2014. Accessed August 16, 2023. accessdata.fda.gov/drugsatf...

3US Food and Drug Administration (FDA). Real-world Evidence from a Narrow Therapeutic Index Product (Levothyroxine) Reflects the Therapeutic Equivalence of Generic Drug Products. Updated November 19, 2020. Accessed August 16, 2023.

4Synthroid [package insert]. North Chicago, IL: AbbVie Inc; 2017.

Date of Last Review: August 14, 2023

medical.lilly.com/us/produc...

This links to the FDA's DailyMed information:

MOUNJARO- tirzepatide injection, solution

dailymed.nlm.nih.gov/dailym...

[Hapyjackie in reply to helvella]

Thank you I have read that and am seeing my gp later this month. I was just wondering if anyone has some personal experience of using the two drugs.

Thanks again

[RedApple Administrator in reply to Hapyjackie]

This link will show you previous posts about weight loss injections. Might be helpful healthunlocked.com/thyroidu...

Also, please be aware that scammers lurk here, waiting to send you a message about where you can buy weight loss medications without prescription. In case this happens, do read our scammer warning post and act on the advice it contains. healthunlocked.com/thyroidu...

[Sunflower64 in reply to Hapyjackie]

I know a couple of people who have been on Wegovy which is similar. It works by suppressing appetite which could result in not eating enough calories. That is bad for hypos as it will lower metabolism further. One person I know went off it because she actually gained some weight while eating less, which is probably a sign of lowered metabolism. And people with hypothyroidism will not lose weight unless optimally treated with thyroid hormone.

Also, you should be aware there is new evidence that you need to stay on these drugs long-term, maybe even permanently, so they should not be seen as a quick fix.

These drugs are also very expensive and not covered by health insurance in many countries.

Warning! There are scammers here claiming to sell Mounjaro for 1/10 of the market price. If someone contacts you by private message, make sure to inform an admin. I received such a scam mail yesterday.

[helvella Administrator]

There appears to be increasing concern that the weight-loss medications can lead to loss of muscle mass.

Bear in mind, hypothyroidism can ALSO lead to loss of muscle mass. Sometimes this is obvious, sometimes less so. The link below refers only to skeletal muscle, but I'd need a lot of convincing that it doesn't also apply to other muscle including the heart.

Skeletal muscle loss and sarcopenia in obesity pharmacotherapy

David C. D. Hope & Tricia M-M Tan

Nature Reviews Endocrinology (2024)

Pharmacological therapies with incretin-based ‘multi-agonists’ are rapidly advancing the therapeutic landscape for obesity. The loss of skeletal muscle mass with these potent weight-loss agents is emerging as a possible side effect. It is therefore important to determine whether multi-agonists increase the risk of sarcopenia in susceptible patients.

The above is all that is accessible without having institutional access.

nature.com/articles/s41574-...

[Sunflower64 in reply to helvella]

restartmed.com/glp-1-agonis...

[Sunflower64]

Correction: Mounjaro is a diabetes 2 drug but some doctors prescribe it off-label for weight loss and in that case it should be covered by health insurance. It is its stronger weight loss version, Zepbound, that most patients have to pay for themselves.

[Transalp]

I wish - it seems impossible to explain to the providers that papillary thyroid cancer is not familial medullary thyroid cancer. Mounjaro is contraindicated for the latter but not for the former, but they seem to apply a blanket ban across all thyroid cancers.