It depends on the product. FDA-approved peptide drugs have been studied, and their side effects and warnings are listed in their prescribing information. Compounded peptides aren't FDA-approved, and products labeled research use only haven't been evaluated for human use. Many peptides sold online have little or no published human trial data.

Its safety in people hasn't been established. BPC-157 isn't approved for human use by the FDA or any other health authority, most research on it is in animals, and USADA notes a concerning lack of published human clinical trial data. It's also prohibited for athletes.

Are Peptides Safe?

Q: What are the side effects of peptides?

For FDA-approved GLP-1 peptide drugs such as Ozempic, the most common side effects listed are nausea, vomiting, diarrhea, abdominal pain and constipation. The label also carries a boxed warning about thyroid C-cell tumors seen in rodents. Side effects differ by drug, so check each one's prescribing information.

Last reviewed October 21, 2026

There's no single answer, because "peptide" covers everything from FDA-approved prescription drugs to vials labeled "not for human consumption." How much is known about safety depends on which kind you're looking at.

The short version

FDA-approved peptide drugs have been studied, and their side effects and warnings are printed in their prescribing information.
Compounded peptides aren't FDA-approved, and the FDA has warned about quality and dosing problems.
"Research use only" peptides haven't been evaluated for human use, and many have little or no published human trial data.

FDA-approved peptide drugs: known, listed side effects

Approved drugs go through FDA review for safety and effectiveness for specific uses, and everything known about their risks goes into the prescribing information. Ozempic (semaglutide) is a good example of what that looks like:

Most common side effects (in at least 5% of patients): nausea, vomiting, diarrhea, abdominal pain and constipation.
Boxed warning: semaglutide caused thyroid C-cell tumors in rodents; it's unknown whether it does in people. It shouldn't be used by anyone with a personal or family history of medullary thyroid carcinoma or with Multiple Endocrine Neoplasia syndrome type 2.
Other listed warnings include pancreatitis, gallbladder disease, kidney problems from dehydration, serious allergic reactions, and low blood sugar when combined with insulin or certain diabetes drugs.

Other approved peptide drugs have their own lists. The FDA's announcements for Wegovy and Zepbound name similar digestive side effects. A prescriber can tell you which warnings apply to you.

Compounded peptides

Compounding pharmacies make medications for individual patients with a prescription. Compounded drugs aren't FDA-approved. For GLP-1 drugs in particular, the FDA has warned that unapproved versions don't go through its review for safety, effectiveness and quality, that it has seen compounded semaglutide and tirzepatide with false label information, and that it has received reports of dosing errors with compounded semaglutide, some needing hospital care.

For some other peptides, the FDA spent years listing them in "Category 2": ingredients for which it had identified significant safety risks in compounding. Several came off that list in 2026, which isn't the same as being found safe or approved. Where each stands is on our FDA status tracker.

"Research use only" peptides

Products labeled "research use only" or "not for human consumption" aren't approved drugs and aren't made for a specific patient. Take BPC-157, one of the most popular:

It isn't approved for human clinical use by the FDA or any other health authority.
Most of the research on it comes from animal and lab studies.
USADA notes a concerning lack of published human clinical trial data.

"Unknown" isn't the same as "dangerous," but it does mean nobody can tell you its risks in people with the confidence that comes with an approved drug.

Supplements and cosmetics

Collagen peptide powders and copper peptide serums fall under different rules. The FDA doesn't approve dietary supplements or their labels before they're sold; manufacturers are responsible for making sure they're safe. Cosmetics and their ingredients, other than color additives, don't need FDA approval either.

For athletes

BPC-157 is prohibited under the World Anti-Doping Agency's list, in the S0 "non-approved substances" category. If you're tested, check any peptide with your anti-doping organization before using it.

Questions worth asking about any peptide

Is it FDA-approved for the use I have in mind? (Check the tracker.)
Who prescribed it, and which licensed pharmacy made it?
What does its label or prescribing information say about side effects and warnings?
Is there published research in people, or only in animals?

These questions are for a licensed clinician or pharmacist, who can weigh them for your situation. We don't give medical advice.

Frequently asked questions

Are peptides safe?

It depends on the product. Approved peptide drugs have studied, listed side effects. Compounded peptides aren't FDA-approved, and research-use-only products haven't been evaluated for human use.

What are the side effects of peptides?

For GLP-1 drugs like Ozempic, the most common are nausea, vomiting, diarrhea, abdominal pain and constipation, plus a boxed warning about thyroid C-cell tumors seen in rodents. Side effects differ by drug.

Is BPC-157 safe?

Its safety in people hasn't been established. It isn't approved for human use anywhere, most research is in animals, and it's prohibited for athletes.

Are compounded peptides safe?

They aren't FDA-approved. The FDA has warned about false labeling and dosing errors with compounded GLP-1 drugs in particular. Use a licensed pharmacy and follow its label and your prescriber.