Medication Interactions: Compound-Specific Examples

Urgent first

Low blood sugar can become an emergency. Severe low blood sugar can cause seizures; call 911 for seizure, fainting or unresponsiveness. [1] In the US, Poison Help is 1-800-222-1222. See When to Seek Urgent Help After Peptides.

There is no universal "peptide interaction chart"

Peptides differ in how they act, how long they stay in the body and how they are cleared. An interaction listed for one compound tells you nothing about another. This page gives examples from the US labels of specific approved medicines, read 2026-10-22. It is information only, not advice. Do not start, stop or adjust any medicine because of this page; ask your prescriber or pharmacist, who have your full medicine list.

Label examples by compound

Reading the examples

Low blood sugar with diabetes medicines. GLP-1 medicines lower blood sugar. The semaglutide label says hypoglycemia risk goes up when it is combined with insulin or sulfonylureas. [2] Symptoms of low blood sugar include shaking, sweating, a pounding heartbeat and unclear thinking. [1] If you take both kinds of medicine, your prescriber should have planned for this.

Slower stomach emptying and oral medicines. The labels say delayed gastric emptying may affect the absorption of oral medicines. [2][3] The semaglutide label adds that in clinical pharmacology trials with the 1 mg once-weekly injection, semaglutide did not affect absorption of oral medicines, but that in a study with the tablet form, levothyroxine exposure rose by 33%. [2] The label suggests more monitoring for oral medicines with a narrow therapeutic index. [2] What this means for a specific drug is a question for a pharmacist.

Contraceptive pills and tirzepatide. The Mounjaro label includes advice for oral hormonal contraceptive users to consider a non-oral or barrier method for 4 weeks after starting and after each increase. [3] Discuss this with a prescriber; do not decide alone.

Tesamorelin. The label says to monitor for interactions with CYP450-metabolized drugs, because growth hormone may alter the clearance of compounds metabolized by CYP450 liver enzymes, while a study with simvastatin found no significant impact on simvastatin levels in healthy subjects. [4] It also mentions people on glucocorticoid replacement may need maintenance dose changes. [4]

Teriparatide and digoxin. Teriparatide briefly raises calcium, which may predispose to digoxin toxicity. [5]

Unapproved and investigational peptides

Proper evidence not found. The FDA bulk-substances page we read gives no interaction data for BPC-157 and says safety information on proposed routes is limited. [6] For many online peptides, identity and strength are uncertain, so an interaction cannot even be predicted reliably. FDA warns that counterfeit products may contain wrong, too little or too much active ingredient. [7] Never assume a combination is safe because no interaction is listed. See Combining Experimental Compounds: Why Risk Cannot Be Assumed.

Practical, non-advisory points

• Give every clinician and pharmacist a full list of what you take, including unapproved products and supplements.
• Before surgery or sedation, mention peptide medicines: GLP-1 medicines slow gastric emptying, and there are rare reports of aspiration during anesthesia. [2]

Related reading

How Interactions Work, Interactions by Drug Class, GLP-1 Medicines: Semaglutide, Tirzepatide and Liraglutide.