Retatrutide Drug Interactions: What to Avoid

Retatrutide and Slowed Gastric Emptying

Retatrutide’s GLP-1 component slows gastric emptying, which can affect the absorption of oral medications. Drugs that need to reach peak blood levels quickly — such as certain antibiotics, pain medications, and thyroid hormone replacement — may have delayed or reduced absorption when taken with retatrutide. The clinical significance of this interaction depends on the specific drug and the individual’s gastric emptying rate, which is dose-dependent. Taking oral medications at the same time each day and monitoring their effectiveness is the standard recommendation.

Oral Contraceptives

GLP-1 drugs can reduce the effectiveness of oral contraceptives by delaying absorption and reducing peak hormone levels. The effect is most significant during the first 4 weeks of treatment and after each dose increase. Women using oral contraceptives should consider using a backup method during dose escalation and for 4 weeks after reaching the target dose. This recommendation is standard across the GLP-1 drug class and applies to retatrutide as well.

Insulin and Insulin Secretagogues

Combining retatrutide with insulin or drugs that stimulate insulin secretion — such as sulfonylureas — increases the risk of hypoglycemia. Retatrutide itself has a low risk of causing hypoglycemia because its insulinotropic effect is glucose-dependent, meaning it only stimulates insulin release when blood sugar is high. But when combined with other diabetes medications that can cause hypoglycemia independent of blood sugar levels, the risk increases. Dose adjustments of insulin or sulfonylureas may be needed when starting retatrutide.