Peptides: What they are, potential benefits, and safety concerns

Peptides are getting a lot of attention on social media, purporting to support everything from muscle growth and skin health to improved energy, cognitive function, and sleep quality. With all of the buzz, you may be wondering what these compounds are, what benefits they actually offer, and whether they’re safe.

As it turns out, we still have more questions than answers about trendy peptide injections. Here’s what you need to know.

What are peptides and how do they work?

Peptides are short chains of amino acids (the building blocks of proteins) that can have a range of effects on the body. For example, peptides help orchestrate hormone activity, immune defense, tissue repair and growth, control of inflammation, and digestion. You can think of them as smaller and simpler versions of proteins, which are made of longer chains of amino acids. The body can make countless types of peptides by stringing together different amino acids. Each combination of amino acids produces unique — and very specific — functions.

The body can make some peptides on its own. Others are made using the amino acids found in dietary proteins like meat, eggs, or legumes. Peptides can also be synthesized in labs. The lab-made kind are often used in medications, supplements, and injectable products.

What are peptides used for?

You’re likely familiar with some of the peptides your body makes, such as

• insulin, which the pancreas makes to regulate the body’s blood sugar
• endorphins, which are released by the central nervous system to block pain signals and relieve stress
• growth hormone–releasing hormone, which triggers the pituitary gland to make and release growth hormone.

Peptides are also used in some FDA-approved medications to treat diabetes, obesity, certain endocrine disorders, and other health conditions. Injectable insulin for blood sugar control is a peptide. So are GLP-1 medications that treat obesity and type 2 diabetes (among other diseases). Examples include semaglutide (Ozempic, Wegovy) and tirzepatide (Zepbound, Mounjaro).

A growing number of people are also using peptide injections and supplements to enhance their health and fitness. Many of these products, which lack FDA oversight, make various unproven health claims.

Peptide supplements and injections

If you’ve seen peptides being plugged on social media, the hype has mostly zeroed in on injectable peptides with names like BPC-157, GHK-Cu, and TB-500. Do a quick Google search, and you can find injectable products claiming to

• boost athletic performance
• enhance muscle growth
• boost fat loss
• enhance sexual function
• support faster healing
• reduce inflammation
• support anti-aging.

Many of the injectable peptides currently marketed online and by wellness clinics are not regulated or approved by the FDA. Instead, they’re experimental compounds that are typically sold through “gray market” online storefronts and often labeled “for research purposes only.”

You can also find dietary peptide supplements (typically in pill or powder form) like creatine, collagen, and follistatin (which are purported to support muscle growth and recovery and joint health, among other claims) at stores and from various online retailers. These products are also largely unregulated.

Potential benefits of peptides

Different peptides have different functions in the body. So, it’s impossible to quantify the benefits of peptides as a group.

Some FDA-approved peptide medications have proven their value for supporting health after rigorous testing, clinical research, and real-world use. For instance, insulin is essential for helping many people with diabetes control their blood sugar, while GLP-1s have helped millions of people reach a healthier weight.

Far less is known about gray-market injectable peptides. “When you’re talking about peptides being promoted online, those health claims have not been vetted by any expert group, the FDA, or anyone else. The health claims are divorced from data,” says Dr. Pieter Cohen, an associate professor of medicine at Harvard Medical School who studies dietary supplements.

It’s possible that some of these peptides could have real benefits, but evidence for such benefits in people is largely absent. A handful of test tube and animal studies suggests that peptides like BPC-157, CJC-1295, and GHK-Cu might support injury recovery and wound healing, for instance. But large-scale human trials are needed to evaluate the efficacy and safety of certain peptides for specific functions before definitive claims can be made.

Some peptides sold as dietary supplements are backed by varying degrees of research. Creatine, for example, is well studied for its ability to enhance muscle growth and athletic performance. And some evidence suggests that some peptides in eye creams that stimulate collagen could possibly help skin appear more youthful.

Are peptides safe?

Peptide safety varies considerably. FDA-approved peptide medications have been studied in large clinical trials, so we have good data supporting their safety.

For unregulated peptides, however, there’s simply not enough evidence to say if they’re safe or not. “You’re really just experimenting with injecting amino acids into your body,” Dr. Cohen says. What’s more, the studies we do have suggest that some injectable peptides could trigger abnormal immune system responses, leading to allergic reactions (including severe ones like anaphylaxis) or autoimmune issues in some people.

Of equal concern is the fact that unregulated peptides may be contaminated with impurities, according to the FDA. That’s especially true for gray-market injectable peptides. These products may be manufactured under murky circumstances, often overseas, so there’s no way of knowing what could be in them.

What experts say about peptides and long-term safety

We don’t know enough about injectable peptides to say what kinds of effects they may have on long-term health or safety. To understand how these substances may affect the body, we’ll need rigorous clinical trials studying individual peptides, experts say.

What is known: because unregulated injectable peptides may harbor contaminants, you’re taking a chance on your health if you use one. “As a clinician, I do not recommend injecting yourself with peptides,” Dr. Cohen says.

If your goal is to maximize your health, fitness, or performance, focus instead on the basics. “Make sure you’re training adequately, eating right, getting enough sleep, and avoiding alcohol and nicotine products,” he advises.

FAQs

What are some side effects of peptides?

The sparse evidence for most injectable peptides means we have very little data on side effects. Anecdotally, some users report experiencing gastrointestinal issues like nausea, diarrhea, or constipation, as well as headache, fatigue, or irritation at the injection site. Some injections are also thought to potentially increase the risk for inflammation of the pancreas.

Are peptides steroids?

Many injectable peptides are used to enhance performance. So, it can be easy to confuse them with other performance-enhancing drugs like anabolic steroids, which can also be injected.

However, peptides and steroids aren’t the same thing. Peptides are short chains of amino acids. Anabolic steroids are typically synthetic versions of naturally occurring male hormones, such as testosterone.

Peptides are getting a lot of attention on social media, purporting to support everything from muscle growth and skin health to improved energy, cognitive function, and sleep quality. With all of the buzz, you may be wondering what these compounds are, what benefits they actually offer, and whether they’re safe.

As it turns out, we still have more questions than answers about trendy peptide injections. Here’s what you need to know.

Image: © Peter Dazeley/Getty Images