Everyone’s Talking About Peptides. But What Can They Actually Do for Your Brain?

Peptides are having a moment.

If you spend any time in the wellness world, you’ve probably noticed. There are peptides for muscle recovery. Peptides for weight loss. Peptides for better skin. Peptides for sleep. There is even one people use to get tan.

And increasingly, I’m hearing about peptides for the brain.

Patients are asking about Selank for anxiety, Semax for focus and brain fog, and BPC-157 for just about everything. Some have already found clinics that will prescribe them. Others are ordering products online after hearing about them on TikTok, Reddit, or a podcast.

This isn’t particularly surprising to me. I work in integrative psychiatry, and many of my patients are already comfortable thinking beyond traditional medication. They take magnesium and L-theanine. They track their sleep. They’ve tried IV infusions, adaptogens, creatine, probiotics, nootropics, or supplements with ingredient lists long enough to require scrolling.

Some of those things have good evidence behind them. Some have interesting but preliminary evidence. Some mostly have excellent marketing.

Peptides are particularly interesting because they don’t fit neatly into any of those categories.

First, what exactly is a peptide?

A peptide is simply a short chain of amino acids, the same basic building blocks that make up proteins. Your body makes peptides naturally, and they act as signaling molecules throughout the body.

So peptides aren’t inherently fringe medicine. Insulin is a peptide. GLP-1 medications grew out of peptide biology. There are many legitimate, well-studied peptide-based medications.

The word peptide, by itself, tells you almost nothing about whether something works.

That’s important, because online, “peptide” has started to function a little like “natural.” It sounds inherently sophisticated, biological, and somehow safer than a pharmaceutical.

It isn’t that simple.

Where psychiatry enters the conversation

The two peptides I’m hearing about most for mental health are Selank and Semax.

Selank is generally marketed for anxiety, stress, and emotional regulation. Semax is more often promoted for focus, cognition, mental energy, and the wonderfully nonspecific problem we now call “brain fog.”

And here’s where this gets interesting: these aren’t just compounds someone dreamed up on TikTok. There is actual science behind them.

Selank has been studied in humans, including small studies involving anxiety disorders. Semax has a research literature as well, particularly from Russia, with proposed effects involving neuroplasticity and brain signaling. There are biologically plausible reasons researchers are interested in both compounds.

That gets my attention.

It does not, however, get us all the way to: Selank treats anxiety or Semax treats ADHD and brain fog.

The human studies are limited, much of the research comes from a relatively small number of research groups, and we don’t have the kind of large, independently replicated clinical trials we rely on when deciding whether a treatment meaningfully improves psychiatric symptoms.

This is a distinction that gets lost very quickly online.

A compound can have an interesting mechanism.

It can do something impressive in a mouse.

It can change something measurable in the brain.

It can even look promising in a small human study.

None of those things necessarily mean it will make a person with anxiety, depression, or ADHD feel better.

Psychiatry has learned that lesson many times.

Then there’s BPC-157

BPC-157 may be the celebrity peptide of the moment. It’s promoted for healing, inflammation, gut health, and injury recovery and increasingly for mood and brain health.

The biological research is interesting. The human evidence is remarkably thin.

Recent reviews have found a substantial body of preclinical research but remarkably little human data. That’s a very different evidence base from what you might assume after spending twenty minutes online.

That doesn’t prove BPC-157 doesn’t work.

It means we don’t know yet.

And I think we’re increasingly uncomfortable with those three words.

About that “brain fog”

When someone asks me whether Semax could help their brain fog, I’m often more interested in the first half of the question than the second.

Why are you having brain fog?

“Brain fog” isn’t a diagnosis. It’s a description of an experience: trouble concentrating, feeling mentally slow, forgetting words, losing your train of thought, or just not feeling as sharp as you used to. I see it all the time.

Sometimes it’s ADHD. Sometimes it’s depression or chronic anxiety. Sometimes someone is sleeping five hours a night and wondering why their brain isn’t cooperating. Perimenopause and menopause can play a role. So can medication side effects, cannabis, alcohol, thyroid problems, iron or B12 deficiency, post-viral illness, and a long list of other medical and lifestyle factors.

Often, it’s more than one thing.

So before reaching for something intended to improve cognition, I want to understand what we’re actually trying to treat.

That may sound less exciting than finding the right peptide, but to me, that’s what integrative care is supposed to look like. It isn’t simply adding more things. It’s looking broadly at what might be contributing and deciding which interventions actually make sense.

When “integrative” starts to mean “everything”

There’s another version of this I’m seeing more often.

Someone is taking a prescription medication, several supplements, a GLP-1, magnesium for sleep, something for cortisol, creatine, maybe doing NAD+ infusions, and now considering adding a peptide.

None of those choices is automatically unreasonable.

The problem is that once enough things are added, it becomes surprisingly difficult to know what is doing what.

Did your anxiety improve because of the new supplement or because you started sleeping better? Is the fatigue coming from your medication, the peptide, inadequate calories, or something completely unrelated? Which things are actually helping enough to justify continuing them?

More interventions do not necessarily equal more integrative care.

Good integrative care should actually make us more deliberate about what we add: why we’re using it, what outcome we expect, how long we’re going to try it, what the risks are, and how we’ll know whether it’s working.

Promising is not the same as proven

This may be the most important distinction in this entire conversation.

“Promising” is a real scientific category. It just isn’t the same category as “proven.”

Most treatments we use today were promising before they were proven. New ideas have to start somewhere. Early laboratory findings and small clinical studies are exactly how potentially useful treatments begin to emerge.

A lot can happen between an interesting early finding and a treatment that reliably helps patients.

Larger studies sometimes confirm the early results. Sometimes the effect turns out to be much smaller than expected. Sometimes it disappears entirely. And sometimes an intervention works, but only for a particular group of people or at a dose that creates other problems.

That’s why clinical trials matter.

It’s also why I’m not particularly interested in dismissing Selank or Semax simply because the evidence is early. I’m interested in seeing what happens when they are studied more rigorously.

What I’m less comfortable with is skipping that middle step and marketing an interesting molecule as though the clinical question has already been settled.

Compounded doesn’t mean FDA-approved

This is another point that has become especially confusing as peptides have become easier to find through wellness clinics and telehealth companies.

A medication being available through a compounding pharmacy does not mean the FDA has approved it for anxiety, depression, ADHD, or brain fog.

Compounding has a legitimate and important role in medicine. There are situations where patients need a medication in a dose or formulation that isn’t commercially available.

But compounded medications are not FDA-approved medications. The FDA does not evaluate compounded drugs for safety, effectiveness, and quality before they reach patients in the same way it evaluates an approved drug.

That distinction becomes particularly important when the treatment itself is still experimental.

Being able to obtain something and having strong evidence that it treats a particular condition are two separate questions.

So how do I think about a new treatment like this?

I don’t think the right question is simply, “Is it natural?” or “Is it FDA-approved?”

I want to know what the evidence actually looks like.

Has it been studied in humans, or are we talking primarily about cells and animals?

Was it studied for the condition we’re trying to treat?

Was there a control group?

Have independent researchers reproduced the findings?

Do we have reasonable information about dosing, side effects, interactions, and longer-term safety?

And perhaps most importantly, what problem are we actually trying to solve?

Those questions don’t make a treatment conventional or integrative. They’re just good clinical questions.

Where I land on peptides right now

I’m watching this space closely.

I wouldn’t be surprised if some peptides eventually find a meaningful place in psychiatry. Selank and Semax, in particular, raise interesting questions that deserve better research.

I also understand the appeal.

If you’ve tried an SSRI that affected your sex drive, a stimulant that made you anxious, or several medications that simply didn’t help enough, hearing about something that supposedly improves focus or calms the nervous system without the usual tradeoffs is understandably attractive.

But we’re living in a strange moment in medicine where the distance between an interesting molecule and a wellness treatment can sometimes be one podcast episode and an online checkout page.

That doesn’t mean the molecule is useless.

It means we should know which part of the story we’re actually in.

For Selank, Semax, BPC-157, and many of the other peptides currently circulating in the wellness world, there are interesting signals. There are plausible mechanisms. There are reasons to keep studying them.

There are also a lot of unanswered questions.

I’m comfortable being interested before I’m convinced.