Peptides and Their Use

Dr. Hyung T. Kim, MD, DiplABIM, DiplABAARM, DiplABLM

 

Interest in peptides has surged in recent years. At GenAge Center, we’re seeing more and more people asking about them, and in some cases, individuals have already started using peptides on their own. This is happening despite clear restrictions from the U.S. Food and Drug Administration on their use outside of specific approved indications.

 

As curiosity continues to grow, it’s important to separate hype from evidence. Understanding what peptides are, how they function in the body, and the regulatory landscape surrounding them is essential for making informed, safe decisions. In the following, we’ll walk through what you need to know about peptides, their potential applications, and the considerations that should guide their use.

 

What Peptides Are and What They Do

 

Peptides are small proteins that have remarkable biological activity. GLP-1s like Ozempic and Zepbound for weight loss, are just two examples, because there are peptides that do pretty much anything you might want. Some of the most popular are:

 

• Healing peptides. These peptides are shown to speed healing by improving blood flow, reducing inflammation, and other critical functions. The two most common are BPC-157, a naturally occurring substance found in gastric juices, and TB-500, a synthetic fragment of a different naturally occurring substance. These peptides can be administered by mouth, subcutaneous injection (into the fat under skin), or directly into areas to be healed, like joints. They are generally well-tolerated and have few side effects.

 

• Growth hormone (body composition) peptides. These peptides help to increase muscle mass and decrease fat by increasing the natural production of growth hormone and insulin-like growth factor 1. They are synthetic, with the most common being sermorelin (GRF), CJC-1295, ipamorelin, and tesamorelin; GRF and tesa are FDA-approved. They are administered by subcutaneous injection at night, to mimic the body’s natural production of growth hormone. They are well-tolerated but may cause flushing and/or headaches; there’s a concern they could make cancer grow. Because of these, we recommend a cancer screening first. At GenAge we look ahead and have our patients’ safety at the forefront.

 

• Mitochondrial (energy) peptides. These peptides are shown to help improve energy and/or exercise performance by improving the function of mitochondria, the parts of our cells which generate energy. The two most common are MOTS-c and SS-31; SS-31 (aka Elamipretide) is FDA-approved. They are given by subcutaneous injection or intravenous infusion (by needle directly into veins). They are generally well-tolerated, with risk of dizziness, headaches, gut symptoms and fatigue.

 

• Nootropic (brain health) peptides. These peptides may help to improve cognition, learning and memory by providing factors shown to aid growth and healing of neurons, the cells that comprise the brain and nerves. The two most common are Cerebrolysin and Semax; Cerebrolysin is a treatment for brain injury, dementia & stroke approved in over 50 countries (e.g., China, Germany, South Korea), but not the U.S. They are administered by subcutaneous injection or intravenous infusion, and for Semax by nasal spray. They are generally well-tolerated, with risk of headaches, sleep disturbances and restlessness.

 

These are just four popular classes of peptides.

 

How to Use Them

 

Like prescription medications, peptides are powerful, so their use should be rigorous, with at least five parts to their use:

 

1. Clear purpose. Just like antibiotics are used to treat infections or certain medications are used to manage diabetes, peptides should always be used with a specific goal in mind. They are not meant to be taken casually or just for general “anti-aging.”

 

For example, growth hormone–related peptides are typically considered when there is a clear need, such as improving muscle mass or addressing unhealthy levels of visceral (belly) fat. The focus should always be on targeted, medically appropriate outcomes rather than broad or vague goals.

 

2. Progress measures. Just like we track improvement when using antibiotics or monitor blood sugar levels with diabetes medications, peptide therapy should also be guided by clear, measurable outcomes.

 

For example, with growth hormone–related peptides, we don’t just rely on how someone feels. We look at specific markers like IGF-1 levels, changes in muscle mass and visceral (belly) fat through tools like a DEXA scan, and overall health indicators such as kidney and liver function. It’s also important to ensure there are no underlying concerns, like cancer, before continuing therapy.

 

This kind of structured monitoring helps ensure treatment is both safe and actually delivering meaningful results.

 

3. Personalized dosing. Since most peptides haven’t been studied like FDA-approved drugs, it’s especially important to personalize and monitor dosing. For example, the typical starting dose for sermorelin may be 0.2 mg at night, but it should be personalized to the patient’s gender and size, physiological functions, and responsiveness.

 

4. Reliable sourcing. Sourcing peptides is one of the most important and often most challenging parts of using them safely. Many traditional pharmacies, including some compounding pharmacies, do not carry a wide range of peptides. At the same time, there are many online and alternative sources that are largely unregulated. Unfortunately, testing has shown that some of these products may not contain what they claim, and in some cases may include contaminants.

Whether someone is exploring peptides independently or working with a provider, prioritizing safety and quality is essential. A general approach to consider:

• First, obtain peptides through a prescription filled by a reputable compounding pharmacy (they are regulated by state and federal authorities)
  • Second, look to the same vetted sources that trusted compounding pharmacies use
  • Third, if sourcing directly, choose a lab that demonstrates transparency and quality standards, including:
• Clear documentation of manufacturing practices such as cGMP compliance
• Up-to-date, third-party Certificates of Analysis (COAs)
• S.-based manufacturing, when possible, ideally with FDA registration

 

Taking these steps helps reduce risk and ensure you are using a product that is both safe and accurately formulated.

 

5. Expert guidance. Who to engage to guide peptide therapy is also difficult and important. Most medical providers lack training, experience and appetite. Most trainers and other non-medical providers lack medical knowledge and accountability – this includes your workout buddies and your favorite AIs. My advice – especially for injection peptides – is to go with (a) a licensed medical provider with (b) formal training in peptide therapy, (c) experience using peptides not only with patients but also on themselves, and (d) patients who vouch for their effectiveness.

 

It’s no wonder there is so much interest in peptides! These little proteins have remarkable biologic activity, and the FDA restricts them – which these days just heightens interest. If you’re interested in them, just make sure you treat them like prescription medications: have a rigorous process for their use and get guidance from someone who not only is knowledgeable, but also accountable.

 

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Dr. Hyung Kim is a devoted family man, former hospital system president, and a physician at GenAge Center, a medical practice in Grand Rapids, Michigan specializing in longevity and wellness. He is triple board-certified: by the American Board of Anti-Aging and Regenerative Medicine, the American Board of Internal Medicine, and the American Board of Lifestyle Medicine. His M.D. is from Johns Hopkins, and his internal medicine training is from the University of Michigan (Go Blue!). His greatest wellness weakness is his wife’s triple-chocolate chip cookies.