What's the Deal with Peptides?
Are peptides a biohacking breakthrough — or a shortcut with hidden risks?
Prefer to listen to a human conversation?
A patient came in having just joined what he described as a longevity and wellness program — one of those exclusive, ultra-discreet operations you find out about through a friend of a wealthy friend. He forwarded me his new regimen. It was a long PDF, full of tables and acronyms and numbers I didn’t recognize: BPC-157, TB-500, sermorelin.
I went line by line and Googled everything. And I kept arriving at the same place: limited data, no FDA approval, no clear prescribing guidelines for humans. I told him honestly that I couldn’t recommend these things, that I didn’t have the clinical experience with them, and that the evidence wasn’t there yet.
That was a couple of years ago. Since then, peptides have moved from the back corner of bodybuilding forums to the front pages of wellness influencers, biohacking podcasts, and med spa menus. Now they’re being casually offered alongside Botox and IV drips, presented as something natural, something your body basically already makes, something with essentially no downside.
So we thought it was time to slow down and ask the bigger question:
What actually are peptides? Why is everyone suddenly talking about them? And what does the evidence actually say?
The Claim
The pitch for peptides goes something like this: these are naturally occurring compounds — short chains of amino acids that your body already produces — and when used therapeutically, they can help with nearly everything people want most. Fat loss. Muscle gain. Better skin. Faster recovery from injury or illness. Gut healing. Immune optimization. And unlike the pharmaceutical drugs your doctor prescribes, peptides are framed as natural, low-risk, and available right now — no referral, no prescription, no insurance, no waiting. If the FDA hasn’t approved them yet, that’s presented not as a safety signal, but as institutional gatekeeping. One podcast claimed that 75,000 people had already used a particular peptide with no adverse effects. Why wait?
Why It’s Going Viral
The appeal of peptides is not irrational. It’s rooted in some genuinely real things that deserve to be named.
Fitness and wellness culture have gone thoroughly mainstream over the last decade. The desire to not just be healthy but to optimize — to reach peak performance, to slow aging, to get ahead of disease before it happens — has moved from elite sports medicine into suburban gyms and Instagram reels. In that context, peptides fit neatly into an existing cultural narrative about biohacking and “medicine 3.0.”
GLP-1 agonists — semaglutide, tirzepatide — were a kind of gateway. Most people now know someone who has had a visible, significant result on a GLP-1. And GLP-1s are peptides. That’s not always made explicit in the conversation, but it’s part of why the category as a whole has gained credibility. If one peptide can do that, why not others?
There’s also a real and understandable undercurrent of distrust. Many people have had experiences of feeling dismissed by the medical system, or of watching regulatory agencies make decisions that seemed financially rather than scientifically motivated. When the framing is that the FDA and “big pharma” are gatekeeping treatments that could genuinely help you, and when you can access those treatments today with one click, the calculus can feel simple.
And then there’s the K-shaped economy reality: people at opposite ends of the financial spectrum are both drawn to peptides, but for different reasons. Wealthy patients join exclusive longevity practices that quietly incorporate them as part of a full optimization protocol. Patients with fewer resources, who can’t afford adequate conventional care or who have run out of options for a chronic condition that medicine hasn’t answered well, are buying research chemicals online and doing their best with dosing information from Reddit. The middle — the patient with a solid PCP and good insurance — is less likely to be asking. And that middle is shrinking.
The way these compounds are framed matters enormously. The podcasts and influencers promoting peptides spend the vast majority of their time describing biological mechanisms: this peptide binds to this receptor, triggers this cellular process, and your body does this remarkable thing. It’s genuinely fascinating science. What gets almost no airtime is the adverse effects, the contraindications, the limits of the human data, or the quality of the studies behind the claims.
What the Science Shows
Let’s start with what’s true: peptides are real, they do things, and the category holds genuine therapeutic promise. Compared to small molecule drugs, peptides tend to have lower immunogenicity and fewer unintended drug interactions, precisely because of their specificity — they tend to act like a lock and key, binding to a particular receptor rather than wandering through the cell doing unpredictable things.
The science of peptide drug development has also advanced significantly over the past few decades. Manufacturing is cheaper. Identification of promising peptide sequences is faster. Hundreds of compounds are in research and development pipelines right now. This is a genuinely exciting area of medicine.
But the evidence for individual compounds varies dramatically — and that distinction matters.
Some peptides have substantial human clinical trial data and FDA approval. Insulin. Semaglutide and tirzepatide. These have been through rigorous phase III trials. We know their benefit profiles. We also know their risk profiles, because going through that process is precisely what generates the information needed to prescribe safely.
Some peptides have clinical data in humans and are approved in other countries or for very specific indications in the US. Thymosin alpha-1, for example, has been studied extensively in the treatment of hepatitis B and C and as a cancer adjuvant — though there’s no FDA-approved product in the US. Tesamorelin is FDA-approved specifically for reduction of visceral fat in HIV patients with lipodystrophy. And because it went through phase III trials, we actually know what it does to people: arthralgia in 13% of patients, injection site reactions in 17%, peripheral edema in 6%, meaningful increases in risk of glucose intolerance and diabetes compared to placebo. None of that means it’s a bad drug — in the right clinical setting it’s a useful one. It means that when a compound goes through proper testing, side effects emerge. They always do.
Retatrutide — a peptide acting on the GLP-1, GIP, and glucagon receptors simultaneously — is currently in phase III trials and not yet approved. Phase II data showed remarkable weight loss outcomes. People can’t wait and are buying it on the gray market. That may be understandable, but it means using a drug with no established dosing guidelines for humans and no data on long-term safety.
And then there’s the third category: compounds with little to no human data. BPC-157 and TB-500 — often marketed together as the “Wolverine stack” — are the most widely discussed examples. BPC-157 has meaningful preclinical and animal data for gastric protection, tissue healing, and angiogenesis. One small human study in 12 patients with knee pain exists. There are rumors of phase II trials in ulcerative colitis and multiple sclerosis that were never fully published. TB-500 has no human data at all. These compounds were removed from the list of substances compounding pharmacies can legally use precisely because the safety data isn’t there. They now exist primarily on the gray market, purchased as “research chemicals” technically labeled not for human use.
And the gray market introduces a separate, significant problem: purity and contamination. A 2018 study examining peptides sold on the gray market in Belgium found that purity ranged from 5% to 75% of labeled concentration — and also found high levels of heavy metal contamination, including arsenic and lead. The manufacturing of peptides is technically demanding and storage-sensitive. There is no mechanism requiring that what you’re purchasing contains what it says it does.
Clinical Nuance
None of this is a reason to dismiss patients who are using or curious about peptides — or to assume they’re being reckless. A lot of the people asking about these are people who have been failed by the healthcare system in some meaningful way: patients with fibromyalgia or chronic fatigue syndrome or other conditions where conventional medicine has offered them very little, patients who feel dismissed or undertreated, patients who are watching the people around them make health gains with GLP-1s and wondering what else might be possible.
For patients like that, the offer of something that might help — and that’s framed as safe and natural — is not irrational to consider. Our goal isn’t to shame the interest. It’s to help fill the informed consent gap, because the companies and influencers selling these things often aren’t.
Framing matters. The same patient who was unbothered by injecting an unregulated compound he’d read about online was, a year later, deeply anxious about starting an SSRI — because his physician had walked him through the risks and uncertainties carefully. The information felt different coming through a relationship built on honesty. That’s the role we can play.
If a patient has exhausted conventional options and wants to explore something investigational, that’s their autonomy to exercise. The most useful thing we can offer is: honest acknowledgment of what we don’t know, clarity that this is a drug with potential effects and risks, awareness of the purity and contamination risks of gray market products, and openness to continue the conversation as evidence evolves. That’s not gatekeeping. That’s medicine.
We’re also genuinely hopeful about the category. The science is real. The pipeline is full. If regulatory pathways can be made more efficient and better funded, many of these compounds may eventually reach the market with the safety data needed to use them responsibly. We want that outcome too.
The Antidote
For Patients
Wanting to feel better — to optimize, to recover faster, to get ahead of disease — is not something to feel embarrassed about.
Being curious about peptides doesn’t make you gullible or reckless. These are genuinely interesting compounds with real science behind some of them.
A compound being “natural” or available without a prescription does not mean it has no risks. Anything that does something in your body can also do unintended things.
The absence of a side effect list is not reassurance. It usually means the compound hasn’t been studied carefully enough in humans to generate one.
If you’re considering using a peptide — especially one purchased outside of a clinical setting — you deserve honest information about what is and isn’t known, including the real purity and contamination risks of gray market products.
It’s okay to want more from your healthcare than you’re currently getting. That desire is valid. It deserves to be met with better care — not just better marketing.
Language Clinicians Can Use
“I’m really glad you brought this up. There’s a lot of information out there about peptides — some of it exciting, some of it misleading — and I’d rather we talk through it together than have you navigate it alone.”
“These are drugs. I know they’re not presented that way, but anything that affects the structure or function of your body is a drug — and that means there are potential risks, even when we don’t have a full list of them yet.”
“The reason this one doesn’t have a side effect list isn’t because it’s safe. It’s because it hasn’t gone through the testing that would generate that list.”
“I understand why you’re interested in this, especially given how hard it’s been to find answers through the usual routes. I don’t want to dismiss that. Let’s talk about what we know, what we don’t, and what I’d want you to watch out for if you decide to try it.”
“If you’re buying this online, I want you to know that purity is a real concern. What’s labeled on the package may not reflect what’s actually in it.”
“I’m genuinely excited about where peptide medicine is headed. I just want to make sure any decision you make is fully informed — not just by the people who are selling you something.”
I started with this episode after seeing you respond to a post in one of the doc mom groups. I love the podcast and have started to catch up on the other episodes.
Would you consider an episode on the antihistamine regimen people in perimenopause are touting? Benefits/risks?