Retatrutide Interactions: Medicines, Supplements and Study Evidence
Which retatrutide interactions have actually been studied?
A pharmacokinetic study measures how exposure to a substance changes under specified conditions. The following records name the tested medicines. They do not establish an approved treatment regimen.
| Record | Named substances tested with retatrutide | Registry status at this check | What can be concluded |
|---|---|---|---|
| NCT05445232 | Midazolam, warfarin and caffeine | Completed; no results posted | A defined drug-cocktail study exists; its registry does not report the size of any interaction |
| NCT06808802 | Metoprolol | Completed; no results posted | A dedicated oral-metoprolol study exists; a clinical effect cannot be calculated from its design alone |
“No results posted” refers to these registry records. It is not a claim that no publication or sponsor information can exist elsewhere. The records were checked directly, including their intervention lists and results fields.
Retatrutide remains investigational. FDA says it is unapproved and cannot be compounded under federal law. HealthRX.com does not offer it. FDA status
What about other prescription and over-the-counter medicines?
The medicines below are not named as the tested interaction drugs in those two records. That statement describes the scope of the records, not proof that a combination is harmless, harmful, or absent from every possible research source. A separate-drug label or an interaction checker for another GLP-1 medicine cannot create retatrutide-specific instructions.
| Medicines or category being asked about | What the reviewed records can answer |
|---|---|
| Apixaban and rivaroxaban | The named anticoagulant in NCT05445232 is warfarin. Its findings cannot be assumed to apply to these different medicines |
| Clopidogrel | Neither record tests clopidogrel as the named interaction drug |
| Atorvastatin, rosuvastatin and simvastatin | Neither record provides a statin-specific interaction result |
| Bupropion, SSRIs and trazodone | Neither record supplies an antidepressant-specific retatrutide interaction result |
| Gabapentin, pregabalin and opioids | Neither record establishes compatibility or a timing schedule for these combinations |
| Diphenhydramine and zolpidem | Studying midazolam does not establish the interaction profile of these different medicines |
| Finasteride | Neither record tests finasteride as its named interaction drug |
| Metformin | Background use in a diabetes trial is a different question from a dedicated interaction study |
| Prednisone | Neither record provides a prednisone-specific interaction result |
| Proton pump inhibitors (PPIs) | Neither record establishes an acid-suppressant spacing or absorption rule |
| Birth control and estradiol HRT | Neither record establishes contraceptive effectiveness or estradiol exposure with retatrutide |
The published phase 2 diabetes trial permitted participants using stable metformin, alongside participants managed with diet and exercise. That context helps interpret the trial; it does not produce a universal adjustment rule for everyone taking metformin. Diabetes trial, PMID 37385280
Does retatrutide affect birth control or HRT?
The reviewed interaction records do not answer whether retatrutide changes contraceptive reliability. Instructions in a tirzepatide or semaglutide label belong to that product and should not be copied into a retatrutide rule. Estradiol HRT and contraception are also different treatment questions; route, formulation and purpose matter.
The pregnancy and lactation review addresses that separate evidence gap. The testosterone interaction review examines that separate product and source context.
What about vitamins, minerals, herbs and other supplements?
These supplement names are not the tested intervention drugs in the two registry records above. No compatibility verdict or spacing interval for them follows from those records. A supplement's separate literature does not prove what happens when it is used with retatrutide.
| Supplement group | Questions covered here |
|---|---|
| Vitamins and minerals | Calcium, folate, magnesium, vitamin B6, vitamin B12, vitamin D and zinc |
| Amino-acid and related products | 5-HTP, creatine, glycine, L-theanine and NAC |
| Oils and antioxidant products | Alpha-lipoic acid, CoQ10, glutathione, omega-3, quercetin and resveratrol |
| Herbal and mushroom products | Ashwagandha, berberine, ginseng, green tea/EGCG, lion's mane, reishi, St. John's wort and turmeric/curcumin |
| Sleep-related supplements | Melatonin |
This grouping is a way to find the question, not a shared safety classification. A multi-ingredient product also cannot inherit evidence for one named ingredient. The food and supplement study map explains why injection absorption, nutrition and oral-drug absorption are different questions.
Is caffeine different from the other supplements listed here?
Yes, in one specific respect: caffeine is explicitly named in NCT05445232, together with midazolam and warfarin. The old assumption that caffeine was not named in a dedicated record would be incorrect. However, the registry still has no posted results at this check. A measured study exposure would not automatically define a coffee limit, an energy-drink rule or a safe interval for caffeine supplements. Caffeine study record
Can spacing doses prevent an interaction?
No universal retatrutide spacing interval is established by these records. Even where a study measures an oral medicine, its result concerns the specific formulation, exposure and study population. A general “two hours apart” instruction cannot be inferred for all the medicines and supplements in the tables.
Retatrutide trials involve controlled investigational products and defined eligibility criteria. Published obesity or diabetes outcomes do not amount to an interaction table for uncharacterized products sold online. Obesity trial, phase 3 diabetes report
What information should a trial participant bring to the study team?
Bring the actual product names, active ingredients, formulations and current medication list, including nonprescription products. Ask whether the study protocol permits the combination and whether the investigator has information beyond the public registry. Do not stop a prescribed medicine or construct a supplement plan from an evidence-gap table.
Questions about surgery, anesthesia or contrast procedures need the procedural team and study team. A routine interaction list does not supply a fasting, anesthesia or contrast protocol. The more specific warfarin review also remains available.
Frequently asked questions
Does no reported interaction mean a combination is safe?
No. A missing result or an unstudied combination is an evidence gap, not a compatibility finding.
Have retatrutide and caffeine been studied together?
Caffeine is named in completed study NCT05445232. Its registry has no posted results as checked September 15, 2026, so this record does not provide a caffeine limit or timing rule.
Can I use another GLP-1 drug's interaction instructions?
Those instructions belong to the specified product. They do not create an approved retatrutide interaction or conversion chart.
Evidence checked September 15, 2026. Medical review of this revision is pending.
References
- ClinicalTrials.gov. NCT05445232, a drug-drug interaction study of LY3437943 in participants with obesity. Intervention and results fields checked September 15, 2026. Registry
- ClinicalTrials.gov. NCT06808802, retatrutide and metoprolol pharmacokinetics in healthy participants. Intervention and results fields checked September 15, 2026. Registry
- U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. FDA
- Rosenstock and colleagues. Retatrutide for people with type 2 diabetes: a randomized phase 2 trial with placebo and active control. PMID 37385280. PubMed
- Jastreboff and colleagues. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. PMID 37366315. PubMed
- TRANSCEND-T2D-1 phase 3 diabetes trial report. PMID 42250575. PubMed
- Electronic Code of Federal Regulations. 21 CFR 312.7, investigational-drug promotion and commercialization. Federal rule
