TMI but the constipation is REAL

sophie_paris 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.

ingrid_STO said:

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

Saving this. It is the first explanation that did not require me to already understand it.

sophie_paris 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.

One concrete data point for the thread. Practical: whatever you change, write down the date and the reason. In three months the reason is what you will have forgotten, and the reason is what makes the record worth having.

Moderator note: the sourcing question belongs in the vendor section and has been split out. Carry on.