The short answer
Take levothyroxine at least 60 minutes before any GLP-1 dose. Recheck TSH at 6-8 weeks after starting a GLP-1.
Use with cautionGenerally OK with monitoring
Why it matters
Delayed gastric emptying reduces levothyroxine Cmax and bioavailability, particularly when both are taken in the morning.
What to do
Take levothyroxine 60+ minutes before breakfast and any GLP-1 dose. Recheck TSH 6-8 weeks after starting the GLP-1 and after each dose escalation. Adjust levothyroxine dose only on the basis of TSH change, not symptoms.
Ask your prescriber
“I take Levothyroxine. Is Foundayo (orforglipron) safe with it, and what should we monitor?”
How Levothyroxine and Foundayo (orforglipron) interact
Delayed gastric emptying reduces levothyroxine Cmax and bioavailability, particularly when both are taken in the morning.
What to do
Take levothyroxine 60+ minutes before breakfast and any GLP-1 dose. Recheck TSH 6-8 weeks after starting the GLP-1 and after each dose escalation. Adjust levothyroxine dose only on the basis of TSH change, not symptoms.
Before you start Foundayo (orforglipron)
A licensed prescriber reviews your full medication and supplement list before prescribing a GLP-1. If you take Levothyroxine, mention it at your consultation.
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Same question, other GLP-1s
Other things people check with Foundayo (orforglipron)
Full Levothyroxine interaction profile
See Levothyroxine reviewed against every GLP-1 on one page: Levothyroxine + GLP-1 interactions
Sources
Educational information, not medical advice. Always confirm interactions with your prescriber or pharmacist.