GLP-1 Drug Interactions: 8 Medications to Watch

GLP-1 medications slow gastric emptying — that's part of how they work. But slower digestion means other oral medications may be absorbed differently. Here are the interactions that matter most.

Medications That Require Monitoring

1. Oral contraceptives: GLP-1s can reduce the absorption rate of oral birth control pills. While overall absorption may be maintained, the timing shifts. If you're on oral contraceptives, discuss backup methods during the first 4-8 weeks of GLP-1 treatment or after dose increases.

2. Warfarin and other blood thinners: Delayed absorption can alter the time to peak effect. Monitor INR more frequently when starting or adjusting GLP-1 dose.

3. Levothyroxine (thyroid medication): Already requires empty-stomach dosing. GLP-1-induced delayed gastric emptying may further affect absorption. Take thyroid medication at least 30-60 minutes before GLP-1 injection days.

4. Metformin: Generally safe to combine with GLP-1s — in fact, this is a common combination for type 2 diabetes. But GI side effects (nausea, diarrhea) can compound.

5. Sulfonylureas and insulin: Combining with GLP-1s increases hypoglycemia risk. Dose adjustment of the sulfonylurea or insulin is usually necessary.

6. Acetaminophen and NSAIDs: Delayed absorption means slower onset of pain relief. Not dangerous, but relevant for acute pain management.

7. Antibiotics (oral): Some oral antibiotics require consistent absorption timing. Discuss with your prescriber if you need antibiotics while on GLP-1 therapy.

8. Foundayo-specific: CYP3A4 inhibitors: Strong CYP3A4 inhibitors (certain antifungals like itraconazole, HIV medications) significantly increase orforglipron blood levels. Foundayo's prescribing information caps the dose at 9mg daily when combined with strong CYP3A4 inhibitors. CYP3A4 inducers (rifampin, certain seizure medications) reduce orforglipron effectiveness.