What Are Peptides?
If you haven’t seen peptides in the news lately, we’d be surprised. Rex is here to break down what they are, what they do, and what to consider if you’re wondering whether peptide-based treatment may be worth exploring.
By The Curious Pug · Published 2026-08-04T13:17:00.000Z
Peptides have moved from research settings and niche wellness conversations into the mainstream. They’re now being discussed in connection with everything from weight loss and recovery to skin health, energy, and longevity. But all that attention doesn’t necessarily make it clear what peptides actually are.
Rex is here to break it down without the hype. We’ll explain what peptides are, what they actually do, how FDA-approved and compounded medications differ, what Rex plans to offer, and what to consider if you’re wondering whether peptide-focused care may be worth exploring.
Peptides, Explained in 60s
At the simplest level, peptides are short chains of amino acids, the same building blocks your body uses to make proteins. Your body needs proteins; they are essential molecules that build and repair tissues, carry signals, and drive the chemical reactions that keep you alive.
To break it down for you (pun intended), let’s use the example of LEGO®:
- An amino acid is one LEGO piece.
- A peptide is a smaller structure made by connecting two or more LEGO pieces.
- A protein is a larger, more complex LEGO model built from many connected pieces.
But being smaller doesn’t mean peptides are unfinished or unimportant. Many peptides have important jobs of their own. Some carry instructions that tell cells how to respond, almost like messages being sent throughout the body. They deliver those instructions by attaching to specific spots on cells, called receptors. Other peptides help defend the body against harmful microbes, support immune function, or take part in tissue growth and repair. Together, these different roles allow peptides to help regulate many of the processes that keep the body functioning.
Your body naturally produces many peptides. Insulin, oxytocin, and glucagon are all familiar examples. Each one carries out a different function, which helps explain why “peptides” shouldn’t be treated as one type of treatment with one expected result.
That variety is also what makes peptides so useful in medicine. Rather than asking what all peptides do, the better question is what a particular peptide does and how it may be used.
Amino acids are individual building blocks. Peptides connect a few of those blocks, while proteins form larger, more complex structures.
What Do Peptides Do, and How Are They Used?
In actual care, peptide-based medications are used across a wide range of treatment areas, including:
- Weight and metabolic health
- Hormone signaling
- Recovery and repair
- Skin health
- Bone health
- Sexual health
It’s why at Rex we organized our treatment programs the way we did, rather than expecting you to already know which peptide to look for.
The point isn’t that one peptide can do all of those things. It’s that different peptides can be used to target different processes in the body.
How a peptide is taken also depends on the medication. Many are given by injection because the digestive system can break them down before the body can absorb them. Others may be available as tablets, nasal sprays, drops, or topical treatments. The delivery method matters because it can affect how much of the medication reaches the body and how it works.
Peptide-based care can cover a lot of ground, but the medications aren’t all made or reviewed in the same way. That’s where the difference between compounded and FDA-approved medications becomes important.
Compounded vs. FDA-Approved
We won’t go too far into the details here because we’ll have future blog post dedicated to compounded and FDA-approved medications. For now, the main difference is how they’re made and reviewed.
- FDA-approved medications have been reviewed by the FDA for safety, effectiveness, quality, and a specific intended use.
- Compounded medications are prepared by licensed pharmacies based on a prescription for an individual patient. They are not FDA-approved, which means the finished medication isn’t reviewed by the FDA before it is provided to the patient.
Compounding can give a licensed provider more flexibility when an FDA-approved medication doesn’t meet a patient’s medical needs. Depending on what is legally and clinically appropriate, that may include a different dose, formulation, or delivery method.
At launch, Rex is choosing to focus on compounded peptide-based medications. This allows us to begin with a simpler, more focused set of treatment programs and formulations. FDA-approved medications may be added as Rex expands, but they won’t be part of our initial peptide-focused launch.
If there’s an FDA-approved medication or another treatment you’d like to see Rex offer, contact us and let us know. For now, let’s look at what Rex is planning to offer.
What Rex Plans to Offer
Rex plans to begin with a focused lineup of compounded peptide-based medications and related treatments.
Starting Options
- Semaglutide and tirzepatide: GLP-1-based medications for weight management and metabolic health
- Sermorelin: Growth hormone support
- GHK-Cu: Skin and hair health
- Glutathione: Antioxidant support
- NAD+: Cellular energy and healthy-aging support
NAD+ isn’t technically a peptide, but it is commonly offered alongside peptide-focused care and is part of what Rex plans to make available.
On Rex’s Radar
In July 2026, the FDA’s Pharmacy Compounding Advisory Committee, or PCAC, issued favorable recommendations for six additional peptides. Those recommendations are not final FDA approval and don’t make the peptides immediately available for compounding. If the FDA adopts the recommendations and the treatments become available through our pharmacy partner, Rex plans to offer them.
- BPC-157: Gut health and recovery
- KPV: Inflammation and wound healing
- TB-500: Recovery and wound healing
- MOTS-c: Metabolic and bone health
- Semax: Brain health and migraine-related care
- Epitalon: Sleep support
This is our starting point, not a permanent limit. Rex plans to continue expanding its peptide-focused options as additional medications become legally available through our care and pharmacy partners.
Every treatment still requires a prescription from a licensed provider, and availability may vary by state, pharmacy, and individual eligibility. That leads to the question most people have when considering this type of care: are peptides safe?
Are Peptides Safe?
The short answer is yes, peptide treatments can be safe when they’re appropriately prescribed, prepared, and monitored. But no peptide is automatically safe for every person or every use.
The fact that your body naturally produces peptides doesn’t make every peptide-based medication risk-free. Safety depends on the specific medication, dose, delivery method, your health history, and any other medications you’re taking. Side effects also vary. Depending on the treatment, they may include injection-site reactions, nausea, headaches, fatigue, digestive changes, or changes to hormone levels.
Where the medication comes from matters too. Peptides sold online as “research use only” products may be of unknown quality and aren’t meant to be used as prescription treatment. Peptide-based medications should come through a licensed provider and a licensed pharmacy, not an unverified online seller.
A licensed provider should review your medical history, current medications, and the treatment you’re considering before deciding whether it is appropriate. Completing an intake doesn’t guarantee a prescription, and anyone prescribed treatment should follow the provider’s instructions and report side effects or concerns.
That clinical oversight is a major part of how Rex is approaching peptide-focused care.
How Rex Is Approaching Peptide-Focused Care
Rex isn’t designed as an online shelf where you choose a prescription medication and check out. The process starts with learning about your options and completing a secure medical intake.
A licensed provider reviews your health information, asks follow-up questions when needed, and determines whether a prescription is medically appropriate. If treatment is prescribed, a licensed pharmacy partner prepares and ships the medication. Rex brings the platform, treatment information, and overall experience together so those steps feel connected and easier to navigate.
Our goal isn’t to convince everyone that peptides are the answer. It’s to make peptide-focused care easier to understand and access, so you can explore your options and decide whether taking the next step feels right for you.
For more information about Rex’s planned treatment programs and launch updates, visit the Rex homepage.