Are Peptides Safe? 6 Safety Factors That Everyone Should Know About Peptides

Many peptide products are marketed as “natural” because they’re based on peptides that occur naturally in the body. But that doesn’t mean the product itself is automatically safe.

You can think of peptides as belonging to one of two groups: those with FDA approval and those without. Those with FDA approval are usually backed by studies in which large groups of people participated. These studies helped establish well-understood safety profiles.

The other group of peptides have not faced the same level of research and testing. These peptides are still experimental. Some have only been tested in laboratory or animal studies. And others are sold as “research-use only” peptides that aren’t intended for people to use.

1. ‘Natural’ doesn’t always mean safe

Peptides are small chains of amino acids (the building blocks of proteins). Your body naturally produces many peptides that regulate metabolism, growth, immune function, and other processes. That can make synthetic (lab-made) versions of these peptides seem inherently safe.

But “natural” doesn’t always mean risk-free. A peptide can still cause side effects depending on the dose, how it’s used, or how it’s made. Synthetic peptides may also behave differently than the peptides your body produces naturally.

2. Many peptide products lack human clinical studies

The amount and quality of research varies widely from one peptide product to another. Some peptides have been developed into FDA-approved medications backed by years of human clinical research. Others remain experimental.

FDA-approved peptide medications have typically been evaluated in clinical trials involving large groups of people. These studies help determine whether a medication works, the appropriate dosage, and its potential side effects and risks.

Many experimental peptides, however, have only been evaluated in laboratory or animal studies. This early research can identify promising possibilities. But it can’t determine whether a peptide will work or be safe for people to use. It also means there’s limited information about how to take these peptides, how long they can be taken, and their best dose.

And if a peptide is sold in a different dosage form than the one studied, such as an oral pill instead of an injection, the available research may not apply to that product.

3. FDA-approved, compounded, and research-use only peptides aren’t the same

The type of peptide product you’re considering can make a significant difference when it comes to safety.

FDA-approved peptide medications have been reviewed for safety, effectiveness, and manufacturing quality for specific uses. They’re made in FDA-registered facilities and are required to follow strict manufacturing standards. Some of these FDA-approved peptides include semaglutide (Wegovy, Ozempic) and teriparatide (Forteo, Bonsity).

Compounded peptide medications are prepared by pharmacies to meet an individual’s needs. Because of this, they don’t go through the FDA-approval process. Some compounded peptide products use ingredients found in FDA-approved medications, such as semaglutide. But others may contain experimental peptide ingredients — when legally permitted and if pharmaceutical-grade sources are available.

Research-use only peptides are laboratory products that aren’t intended for people to use. They may be sold online without a prescription. But they may not meet pharmaceutical standards for composition, purity, potency, or sterility.

Many compounded and research-use only peptides are also experimental. That means there isn’t evidence from large, well-designed human studies that they’re safe or work well for their promoted uses.

Good to know: The FDA is currently reviewing if certain experimental peptides, such as BPC-157 and MOTS-c, should be added to the 503A Bulks List. This list identifies bulk drug substances that pharmacies can use to compound medications. But it isn’t the same as FDA approval. And even if they’re added, pharmacies would still need to use pharmaceutical-grade peptide ingredients from FDA-registered suppliers, which may not be readily available.

4. Marketing claims aren’t the same as scientific evidence

Peptide products may be promoted for muscle growth, faster recovery, longevity, or several benefits at once. But a marketing claim isn’t proof that a product works.

Be cautious of claims supported mainly by:

• Influencer endorsements or personal testimonials (which may not even be from real people)

• Before-and-after photos

• Laboratory or animal studies presented as proof of human benefits

• Phrases such as “clinically proven” without links to published human research

• Promises of dramatic results without side effects or risks

The most useful evidence comes from well-designed human studies using the specific peptide for the specific condition being discussed.

5. Peptides can affect more than one part of the body

Many peptides act as signaling molecules. This means they can influence communication between cells and regulate multiple processes throughout the body.

A peptide product intended to affect one pathway may also influence other organs or body systems. Those effects may be helpful, harmful, or still unknown. This is especially important for experimental peptides. That’s because researchers may not yet understand all of their intended and unintended effects, such as a potential risk of worsening certain cancers.

Peptides may also interact with medications or health conditions. A healthcare professional can help evaluate whether a specific product is appropriate based on your medical history and current treatments.

6. Learning about safety is an ongoing process

Clinical trials provide important safety information. But they can’t identify every possible risk. Rare side effects may not become apparent until a medication is used by many more people over a longer period of time.

That’s why FDA-approved peptide medications continue to be monitored after they reach the market. Reports from people using them, healthcare professionals, and manufacturers can help identify rare or unexpected problems. This helps build a better understanding of a medication’s long-term safety.

Compounded and research-use only peptides don’t undergo the same level of premarket testing or ongoing safety monitoring. As a result, less is known about their long-term safety, and important safety concerns may take longer to identify.

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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