Peptide guide

Semaglutide

A GLP-1 receptor agonist studied for blood-sugar control and weight loss, sold as a prescription drug under the names Ozempic and Wegovy.

Semaglutide is the GLP-1 receptor agonist behind Ozempic and Wegovy, FDA-approved drugs for type 2 diabetes and obesity. It has more human evidence behind it than almost any peptide in this catalog, including trials showing around 15% body-weight loss. The catch sits in the supply: the approved product is a regulated prescription drug, and research-grade semaglutide powder is neither that product nor cleared for self-use. The practical questions are how it's dosed and titrated, the gallbladder and pancreatitis cautions that come with it, and how to tell a real source from a scam.

By the Zapify Research team

Reviewed against 10 clinical & research sources · Updated June 2026 · Educational use only

Type: GLP-1 analog31-aa peptide
Route: Subcutaneousonce weekly
Typical dose: 0.25–2.4 mg/wktitrated up
Cycle: Titrate, then holdongoing
Storage: Mixed: ~4 wksSealed: months
Status: Rx drug; powder not approvedsee status

What is Semaglutide?

A long-acting GLP-1 analog and the molecule inside Ozempic and Wegovy, FDA-approved as finished drugs — though research-grade powder is neither.

Semaglutide is a synthetic analog of GLP-1, a hormone your gut releases after you eat. The natural hormone tells the pancreas to release insulin, slows how fast the stomach empties, and signals the brain that you're full. Semaglutide copies that signal, but it's engineered to last far longer. A fatty acid chain bolted onto the molecule lets it cling to albumin in your blood, which shields it from being cleared and stretches its half-life to about seven days. That's why it's injected once a week instead of with every meal.

This is the molecule inside three FDA-approved drugs. Ozempic is approved for type 2 diabetes; Wegovy is approved for chronic weight management. In the obesity trials behind Wegovy, people lost an average of roughly 15% of their body weight over 68 weeks, a result that put semaglutide and the GLP-1 class at the center of how medicine now treats obesity.

The evidence base here is the opposite of most compounds in this catalog. Where BPC-157 rests almost entirely on rat studies, semaglutide has been through large, randomized human trials and is prescribed to millions of people. The questions worth asking aren't whether it works. They're about the gap between the approved drug and what gets sold as research powder.

Semaglutide itself is FDA-approved, but only as a finished prescription drug: Ozempic for diabetes, Wegovy for weight. Research-grade semaglutide sold as loose powder is not that product. It hasn't been through the manufacturing, testing, and labeling that approval requires, it isn't cleared for self-administration, and the dose, purity, and even identity are only as good as the seller's lab work. The approval belongs to the brand, not to a vial of powder.

What is it studied for?

Unusually for a peptide the evidence is mostly human, built on the large randomized SUSTAIN and STEP trials plus cardiovascular outcome data.

The evidence here is unusual for a peptide: it's mostly human. Semaglutide ran through the SUSTAIN program for diabetes and the STEP program for obesity, large randomized trials with thousands of participants, before the FDA cleared it. The cardiovascular outcome data is human too. That's the foundation under everything below, and it's worth weighing against the animal-only research most of these compounds rely on.

Evidence base, by subject

Thousands of participantsHuman randomized trials

MinorAnimal-only evidence

The research clusters in three areas:

Blood sugarThe original use. Semaglutide lowers blood glucose and HbA1c in type 2 diabetes by prompting insulin release when sugar is high. This is what Ozempic is approved for.

Weight lossThe STEP trials showed roughly 15% average body-weight loss over 68 weeks, driven by reduced appetite and slower gastric emptying. This is Wegovy's approved use.

Heart riskIn adults with diabetes and established cardiovascular disease, and separately in adults with cardiovascular disease and obesity or overweight, semaglutide reduced the risk of major cardiac events. The FDA approved it for cardiovascular risk reduction on that data.

The mechanism is well characterized. Semaglutide binds the GLP-1 receptor, which sits on pancreatic cells, in the gut, and in appetite-regulating regions of the brain. Activating it nudges insulin up when glucose is high, slows the stomach so food lingers and you feel full longer, and dampens hunger and food-reward signaling centrally. The weight loss is mostly eating less, not burning more. What's still being mapped is the longer tail: how the drug affects food preference, and what happens to weight and muscle after people stop.

Why people use it

People use it for stalled weight loss, type 2 diabetes, and quieter appetite; it clearly works, but weight tends to return when you stop.

Most people who reach for semaglutide are after one of a few things. These are the reasons they try it, framed as reasons rather than guarantees of outcome:

Sustained weight loss after diet and exercise alone have stalled, which is the use that drove the demand surge.
Type 2 diabetes or pre-diabetes, where lowering blood sugar is the medical goal a doctor is actually treating.
The appetite-quieting effect itself, the reduction in food noise and constant snacking that people report within the first weeks.
Metabolic health broadly, often alongside concerns about heart risk, since the cardiovascular data is part of the appeal.

Unlike most compounds here, the question isn't whether semaglutide works. The human trials are real and the effect sizes are large. The legitimate reasons to be careful are different: it's a powerful drug with real side effects, the weight tends to return when people stop, and buying loose powder means trusting a seller's lab instead of a pharmacy's. The approved versions exist precisely because this molecule does enough that it warrants medical supervision. That's an argument for a prescription, not against the molecule.

How to reconstitute Semaglutide

A 5 mg vial in 2 mL gives 2.5 mg/mL, so 10 units draws the 0.25 mg starting dose — and a one-decimal slip means 2.5 mg.

Research-grade semaglutide arrives as a dry, freeze-dried puck in a vial. The approved pens come pre-mixed and ready to dial; powder doesn't, so it has to be reconstituted before use. The process is the same one used across injectable peptides.

Step 1Start with powderWipe the rubber stopper with an alcohol swab.

Step 2Add bac. waterRun it slowly down the inside wall — never shake.

Step 3Draw your doseThe calculator gives the exact units to draw to.

Wipe the rubber stopper with an alcohol swab first, every time.
Use bacteriostatic water, not plain sterile water and not saline. The trace of benzyl alcohol in it holds back bacteria, which matters because you'll be drawing from the same vial for weeks.
Add the water slowly, running it down the inside glass wall. Don't blast it straight onto the powder.
Don't shake it. Swirl gently and let it dissolve on its own. Shaking foams the solution and can damage the peptide.

A common setup is a 5 mg vial mixed with 2 mL of bacteriostatic water, which gives 2.5 mg/mL. On a U-100 insulin syringe, 10 units then draws 0.25 mg, the standard starting dose, and 20 units draws 0.5 mg. The water doesn't change how much semaglutide is in the vial; it only sets the concentration, which decides how many units you draw. More water means a more dilute mix and a bigger draw for the same dose. The risk with semaglutide isn't ruining the vial, it's that the doses are small and a math error of one decimal place is the difference between 0.25 mg and 2.5 mg. That's exactly what the calculator removes.

Calculate your exact Semaglutide reconstitution →

Dose & units

No approved self-dose exists for powder; the labeled schedule starts everyone at 0.25 mg weekly and steps up monthly to a 2.4 mg weight-management dose.

The approved drugs have defined doses, but those are prescribed and supervised by a clinician who titrates to your response. There is no approved self-dose for research powder. Everything below is the schedule the approved labels and clinics report, not a medical instruction. With semaglutide the supervision isn't a formality, because the side effects scale with the dose and the titration exists to keep them tolerable. Decide what goes into your body with a licensed provider, not with this page.

Typical range

Semaglutide is dosed in milligrams once a week, subcutaneously. The numbers depend on the goal: diabetes maintenance lands around 0.5 to 2 mg weekly, while the weight-management target is 2.4 mg weekly. Nobody starts there.

Titration

Everyone starts at 0.25 mg once a week for the first four weeks. This dose isn't meant to do much; it's there to let your gut adapt before the dose climbs. The standard weight-management schedule then steps up roughly every four weeks: 0.5 mg, then 1 mg, then 1.7 mg, then 2.4 mg as the maintenance dose. The slow climb is the whole point, since the nausea and GI effects are worst when the dose jumps too fast. There's no reward for rushing it.

Cycling

Semaglutide isn't run in cycles the way a recovery peptide is. It's a maintenance medication: you titrate up, then hold the maintenance dose for as long as the goal continues. The relevant warning is the other direction. When people stop, appetite returns and studies show much of the lost weight comes back over the following year, which is why this is treated as ongoing rather than a short course.

Titrateweeks 1–16

Maintainongoing

Because the effective doses are small and measured in fractions of a milligram, the draw on an insulin syringe is tiny and easy to get wrong by eye. The calculator turns your vial size, water, and target dose into the exact number of units to draw.

Get your exact units →

Storage

Dry powder keeps for months at room temperature; once mixed, refrigerate at 2–8 °C and use within about 4 weeks, the contamination limit.

Sealed & drySealed dry powder stays stable for months at room temperature and tolerates shipping heat before you mix it.

ReconstitutedRefrigerate at 2–8 °C in the main compartment and use within about 4 weeks; don't freeze, keep out of light, toss if cloudy.

You'll see longer windows quoted for semaglutide vials, sometimes 28 to 56 days. The longer figures are beyond-use dates from compounding pharmacies that have stability-tested a specific formulation, and they stop applying to a vial you mixed yourself. A vial you reconstituted runs on the conservative four-week clock, because that's how long the preservative in bacteriostatic water reliably keeps the solution clean once you're drawing from it.

That four-week limit is about contamination, not potency; the peptide itself often stays good well beyond it. Reconstitute with plain sterile water instead of bacteriostatic and you drop to a day or two, since there's no preservative holding bacteria back.

Don't freeze a reconstituted vial, keep it out of direct light, write the mix date on the label, and throw it out if the solution ever turns cloudy or discolored, whatever the date says.

Side effects & safety

Mostly GI effects during titration, but watch for gallbladder problems, a pancreatitis warning, and a boxed thyroid C-cell tumor warning; currently permitted in sport.

Semaglutide's side-effect profile is well documented, because it comes from large human trials rather than guesswork. Most of it is gastrointestinal, most of it shows up while the dose is climbing, and most of it eases as the body adapts.

Most common: nausea, vomiting, diarrhea, constipation, and abdominal discomfort, worst during titration and usually fading over a few weeks.
Common: reduced appetite (the intended effect, but it can tip into not eating enough), fatigue, and burping or reflux.
Less often but serious: gallbladder problems, including gallstones, which rise with rapid weight loss; in the adult weight-management trials cholelithiasis was reported in about 1.6% of Wegovy users versus 0.7% on placebo.

Two cautions are not negotiable. Acute pancreatitis has been reported with GLP-1 drugs: severe, persistent abdominal pain, sometimes radiating to the back, means stop and seek care immediately. And semaglutide carries a boxed warning for thyroid C-cell tumors based on rodent studies; whether it causes them in humans is unknown, but it is contraindicated if you or a family member has medullary thyroid carcinoma or MEN 2 syndrome. It's also not recommended in pregnancy. None of this is a call you should make without a doctor.

On anti-doping, semaglutide is currently permitted in sport. It isn't on the WADA Prohibited List, but it has been on WADA's Monitoring Program since 2024, and from 2026 both semaglutide and tirzepatide are tracked in and out of competition to watch for misuse. WADA has signaled it may add GLP-1 weight-loss drugs to the banned list before the 2028 Los Angeles Olympics, so a competing athlete should treat the current status as provisional.

With a drug this well studied, the biggest variable left isn't the molecule. It's whether the vial actually contains semaglutide, at the strength on the label and free of contaminants. That comes down to where you buy it.

How to vet a source

Among the most counterfeited compounds here, with FDA warnings about fakes — insist on a batch-specific third-party COA matching your vial's lot number.

Semaglutide is among the most counterfeited compounds in this market, precisely because demand is enormous and the approved drug is expensive and supply-limited. The FDA has warned about fake and contaminated semaglutide, and independently tested research vials have come back underdosed, mislabeled, or holding a different substance entirely. The approved pens are one thing; loose powder is exactly where the fraud lives. Where you buy matters more than almost anything else here, and the one document that separates a real seller from a gamble is a certificate of analysis: a third-party lab's report on what's actually in the vial.

A real COA shows

An identity test (usually mass spectrometry) confirming the peptide is what the label says.
A purity figure from HPLC, typically 98% or higher.
A lot or batch number that matches the number printed on your vial.
A named, independent accredited lab and a recent test date.

Walk away if

There’s no COA, or it’s a generic image with no lot number.
The “certificate” comes from the seller instead of a third-party lab.
The lot number doesn’t match your vial, or there isn’t one at all.
It’s a flat image you can’t trace back to the lab that issued it.

That's the standard worth holding any seller to, ours included. Ask for the batch-specific COA before you buy, match the lot number to your vial, and don't accept a screenshot in place of a traceable report.

See the Zapify compound catalog →

Common questions about Semaglutide

Is semaglutide FDA-approved?

The molecule is, but only as a finished prescription drug. Ozempic is approved for type 2 diabetes, and Wegovy is approved for chronic weight management. Research-grade semaglutide sold as loose powder is not the approved product. It hasn't been through the manufacturing and testing that approval requires and isn't cleared for self-administration, even though the active ingredient is the same molecule.

Ozempic and Wegovy — what's the difference?

Both are injectable semaglutide. Ozempic is the once-weekly injection for type 2 diabetes. Wegovy is the same injection at higher maintenance doses (up to 2.4 mg), approved for weight management. They reach maintenance through the same 0.25 mg starting dose and step-up titration; the brand mostly signals the approved use and the dose ceiling.

How much weight do people lose on semaglutide?

In the STEP 1 weight-management trial, participants lost an average of roughly 15% of their body weight over 68 weeks at the 2.4 mg dose, far more than placebo. Individual results vary widely. The important caveat: when people stop, appetite returns and studies show much of the lost weight comes back over the following year, which is why it's treated as an ongoing medication rather than a short course.

Why does it have to be titrated so slowly?

The gastrointestinal side effects — nausea, vomiting, diarrhea — scale with the dose and are worst when it jumps. Starting at 0.25 mg for four weeks and stepping up roughly monthly lets the gut adapt at each level. The starting dose isn't meant to be effective; it's meant to be tolerable. Going faster mostly buys more nausea, not faster results.

Can athletes use semaglutide?

As of 2026 it's permitted; semaglutide isn't on the WADA Prohibited List. It has been on WADA's Monitoring Program since 2024, and from 2026 it's tracked in and out of competition alongside tirzepatide to watch for misuse. WADA has indicated it may add GLP-1 weight-loss drugs to the banned list before the 2028 Los Angeles Olympics, so a competing athlete should treat the current permitted status as provisional and verify before relying on it.

References

This page is for research and educational purposes only. It is not medical advice or a recommendation to use any compound. The dose ranges shown are reported by clinics and research literature, not validated medical standards, and Semaglutide is not FDA-approved. Talk to a licensed medical provider about anything you put in your body.