GLP-1 and gastroparesis — what worked for you?

PharmacoVig_BOS said:

Heartburn management on constipation: Gaviscon before bed has been my savior.

Drug interaction alert relevant to constipation: if you take oral levothyroxine (Synthroid), GLP-1 agonists can reduce absorption due to delayed gastric emptying. My TSH drifted up after starting semaglutide.

Solution: take levothyroxine on an empty stomach, 60 minutes before any food, and have your TSH rechecked 6-8 weeks after starting or changing GLP-1 dose. My endo had to increase my Synthroid by 12.5mcg.

PeptideChemSF said:

Sulfur burps on constipation — the most underrated side effect nobody warned me about.

Thank you for spelling out the reasoning rather than just the conclusion.

PharmacoVig_BOS said:

Heartburn management on constipation: Gaviscon before bed has been my savior.

Gastric emptying studies and constipation: semaglutide delays gastric emptying by ~40% at steady state, as measured by acetaminophen absorption testing and scintigraphy[1].

Clinically relevant implications:

• Explains early satiety and nausea
• Affects absorption of co-administered oral medications
• Creates aspiration risk for procedures under anesthesia
• Contributes to constipation via slowed GI transit

Importantly, the gastric emptying delay attenuates with continued use (tachyphylaxis), which correlates with the transient nature of GI side effects.

One concrete data point for the thread. Worth stating the units and the reference range whenever you post a number here. A large fraction of the apparent disagreement in these threads is two people using different units and both being right.

Moderator note: a post naming a supplier has been edited. Discuss suppliers in the review sections, not here. Tagging this one for the weekly digest.