Semaglutide is a glp-1 agonist used for weight loss. Semaglutide is a GLP-1 receptor agonist, a lab-made copy of a natural gut hormone your body releases after eating. In plain terms: it flips on your 'I'm full' signal, so you feel satisfied sooner, eat less, and your blood sugar steadies. It is the active drug in Ozempic and Wegovy.

How much water do I add to Semaglutide?

You can reconstitute Semaglutide with 0.5, 1, or 2 mL of bacteriostatic water. Each option produces a different concentration and syringe draw for the same dose. Use the calculator to see which is easiest to measure.

What does Semaglutide cost per dose?

Cost per dose depends on vial size, price paid, and your dose. Enter your vendor's price in the Semaglutide calculator to see cost per dose and monthly cost.

What is the reference dose for Semaglutide?

The commonly referenced range is 0.25 up to 2.4 mg per week (start low, increase slowly), taken weekly. This is reference information, not a recommendation. Talk to a licensed clinician.

What are the side effects of Semaglutide?

Reported side effects of Semaglutide include: Nausea, diarrhea, and vomiting are the main side effects, usually worst in the first weeks and each time the dose goes up.; Starting at a low dose and increasing slowly keeps them manageable.; It carries a warning about a rare thyroid tumor risk.. Severity and frequency vary by person and dose.

Who should not take Semaglutide?

Semaglutide is generally not appropriate for: A personal or family history of medullary thyroid cancer, or the genetic condition MEN 2; Pregnancy, or trying to become pregnant; A history of pancreatitis, which needs a conversation with your doctor first; Severe stomach-emptying problems (gastroparesis). Talk to a licensed clinician before starting.

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Decoding

Semaglutide_Dosage, benefits & legal status

Also known as Ozempic, Wegovy, Rybelsus, GLP-1 SM, GLP-1 S, GLP-1 (S), sema, EZP-1P, GLP-1 SG, EP-1 S

By the Peptide Decoding Editorial Team

Published July 22, 2026 · Updated August 24, 2026

The drug in Ozempic and Wegovy: a weekly shot that curbs hunger for steady weight loss.

Weight lossGLP-1 agonistFDA-approved

InGLP-1 agonists

31 amino acidsFrom a chemical database

Sequence

▸ See the chain

HAEGTFTSDVSSYLEGQAAKEFIAWLVRGRG

Position 2 is a modified residue that resists the enzyme which degrades natural GLP-1, and position 26 carries a fatty chain that binds to albumin. Together those two changes are why this lasts a week and your own GLP-1 lasts two minutes.

Position 2 · Aib · substitution
Alpha-aminoisobutyric acid, which resists the enzyme that breaks down natural GLP-1. Papers call this position 8, counting from the parent hormone.
Position 20 · K · acylation
A C18 fatty diacid chain that binds albumin. This is what makes it weekly rather than minutes. Papers call this Lys26.
Position 28 · R · substitution
Lysine replaced by arginine so the fatty chain attaches at only one place. Papers call this Arg34.

Positions here count from the start of this 31-residue string. Published papers count from the parent hormone GLP-1, which starts six residues earlier, so their numbers are six higher.

Common vial size5 mg

Dose0.25 up to 2.4 mg per week (start low, increase slowly)

FrequencyWeekly

RouteUnder the skin (also comes as a pill)

StatusFDA-approved

MixYour choice, calculate it

CycledNot cycled

Common vial size is what vendors typically sell, not a recommendation. Enter your own vial in the calculator.

What is Semaglutide?

Plain language first. The technical label stays, but it never stands alone.

Overview

It flips on your 'I'm full' signal, so you feel satisfied sooner, eat less, and your blood sugar steadies. It is the active drug in Ozempic and Wegovy.

The technical version

Semaglutide is a GLP-1 receptor agonist, a lab-made copy of a natural gut hormone your body releases after eating.

What it's used for

People use it to lose weight and steady their blood sugar. It calms appetite and cravings so you feel full sooner and eat less without white-knuckling it.

How does Semaglutide work?

What it does in the body, and where.

Semaglutide copies a single gut hormone, GLP-1. That one target is enough to change how hungry you feel, how fast your stomach empties, and how your body handles sugar after a meal.

01
It docks at the GLP-1 receptor
The same receptor your own gut hormone uses after you eat, so your body reads it as an ordinary fullness signal.
02
Your stomach empties more slowly
Food sits longer, so you stay full for longer. This is also where most of the nausea comes from.
03
Appetite signalling in the brain quiets down
Cravings and food noise drop, which is what most people notice first and miss most when they stop.

Receptors

Acts on one receptor.

What else is it used for?

Each group carries its own evidence level.

Approved means regulators have cleared it for that purpose. Investigational means it is in trials. Early research means it is being studied and is not established.

Weight loss

FDA-approved

Human trialIn a 68-week trial, average weight loss was 14.9% of body weight versus 2.4% on a dummy injection.
Human trial86.4% of people lost at least 5% of their body weight, against 31.5% on placebo.
Human trial34.8% lost at least a fifth of their body weight, against 2.0% on placebo.
Human trialIn the follow-up, people who had lost 17.3% regained 11.6 percentage points within a year of stopping, leaving a net loss of 5.6%. Most of the weight comes back if you stop.

Study

STEP 1 trial, New England Journal of Medicine, 2021

Diabetes and heart health

FDA-approved

Human trialIn people who already had type 2 diabetes, average weight loss was 9.6% versus 3.4% on placebo, so it works but somewhat less well.
RegulatoryApproved as Ozempic in 2017 for type 2 diabetes and as Wegovy in 2021 for weight management.

Often left out

Trial weight-loss figures are often quoted without the follow-up: people regained most of the weight within a year of stopping.

Study

STEP 1 analysis, PubMed Central

The published record

Research index

6,371

Records indexed for Semaglutide400 papers and 100 trials indexed in detail.

261 in humans, 127 of them original studies.

754 registered trials, 18 with posted results among the 100 indexed.

FDA: Named as an unapproved new drug.

Browse the records

In animalsPro

In the labPro

ReviewsPro

Senior author sharePro

Counted from Europe PMC indexing, not read by a person. Human means indexed under humans, which includes reviews and work on human cells. Original studies exclude reviews and lab work on human cells.Last updated 11 September 2026.

Compound field notes

At a glance

Four things to know about Semaglutide

Evidence

FDA-approved

How much, and do you cycle it?

The range, and whether you take breaks.

0.25 up to 2.4 mg per week (start low, increase slowly), weekly. Not cycledHuman study

Taken continuously, with the dose stepped up rather than paused. In the STEP 1 extension people regained about two thirds of the weight they had lost within a year of stopping. The question is whether to stay on it, not when to take a break.

Source: Wilding et al., STEP 1 extension: weight regain after semaglutide withdrawal (Diabetes Obes Metab 2022)

Compare this against the whole library →

How long does it stay in the body?

The half-life, and where the figure comes from.

About 1 weekFDA label

The label states approximately 1 week, and that semaglutide is present in the circulation for about 5 weeks after the last dose.

Source: Ozempic (semaglutide) US prescribing information, section 12.3. DailyMed setid adec4fd2-6858-4c99-91d4-531f5f2a2d79

You can compare this against the whole library to see where it sits.

How do I dose and price it?

Enter your vial and your dose. Pick a mix. We show the draw and the cost.

The vial holds a fixed amount of drug. Adding more water does not make more drug, it just spreads it thinner, so you draw a bigger number on the syringe for the same dose.

Your vial size (mg)

Printed on the vial.

What you paid per vial

Used for cost per dose only.

Your dose (mg)

Commonly referenced range: 0.25 up to 2.4 mg per week (start low, increase slowly)FDA label

Choose your mix

0.5 mL water2.5units · 10 mg/mL

Half a 100-unit syringe

1 mL water5units · 5 mg/mL

One full 100-unit syringe

Easiest

2 mL water10units · 2.5 mg/mL

Two full 100-unit syringes

your own mL

units · —

Enter your own volume

Measuring the water1 mL = one full 100-unit syringe.

Your draw

10 / 100 units

Full calculator with reorder date →Read a syringe →

What it costs

Semaglutide starts at $10.00 across 45 vendors, typically $3.20 – $21.40 per mg.

100 listings, last read Sep 5, 2026. Shipping and card fees are not included.

See all 100 listings →

How do you store it?

Before mixing, and after.

Fridge before first use. Room temperature is fine once in use.

Sealed pens live in the fridge. Once you start a pen it can stay at room temperature for the in-use window on the label (often about 4 to 6 weeks depending on the product). Keep it out of light, do not freeze it, and toss it if it has been frozen or left hot.

What are the side effects and cautions?

Known cautions and warnings for this compound.

Handling note

Vials sold as "GLP-1 SM" or "GLP-1 (S)" are semaglutide. GLP-1 on its own is a hormone and a whole class of drugs, so the bare term does not identify what is in a vial. Check the label for semaglutide.

Who should avoid it

Check these before anything else.

A personal or family history of medullary thyroid cancer, or the genetic condition MEN 2
Pregnancy, or trying to become pregnant
A history of pancreatitis, which needs a conversation with your doctor first
Severe stomach-emptying problems (gastroparesis)

Stop and get help

These are emergencies. Seek care.

Severe stomach pain that spreads to your back, which can signal pancreas inflammation
A lump or swelling in your neck, hoarseness, or trouble swallowing
Vomiting badly enough that you cannot keep fluids down
Sudden changes in your vision
Signs of an allergic reaction such as face or throat swelling or trouble breathing

Common effects

Expected, and usually mild.

Nausea, which is the most common effect and usually worst in the first weeks and after each dose increase
Diarrhea, constipation, and vomiting
Tiredness, which real-world users report far more often than trial write-ups suggest
Burping and reflux
Injection-site redness

What regulators say

FDA: Warning letter to Royal Peptides LLC, MARCS-CMS 734884, August 24, 2026: unapproved new drugs, misbranded
Named as an unapproved new drug
The vendor's product, not the approved Ozempic or Wegovy
Checked 11 September 2026

Where this page says nothing is established, that means nobody has studied it, not that a compound is safe.

Is Semaglutide approved?

And where the numbers on this page come from.

Yes. Semaglutide is FDA approved and available on prescription in the United States.

Approval status
FDA-approved
Route
Under the skin (also comes as a pill)
Checked
August 2026

What has happened recently

In January 2026 the FDA asked that the warning about suicidal thoughts and behaviour be removed from the obesity versions of this drug family after a review found no increased risk. Labels were updated in February 2026.

You can compare this against the whole library, or read how to check a seller.

DoseFrom the drug label. The manufacturer tested this range and a regulator reviewed it.
Vial sizeFrom what vendors typically list; not a recommendation.
Sources
FDA, approval for MASH liver disease FDA, removal of the suicidal-ideation warning (Jan 2026)NIH PMC, semaglutide and alcohol use disorder trial STEP 1 trial, New England Journal of Medicine, 2021 STEP 1 analysis, PubMed Central
Reviewed14 August 2026

What else is like Semaglutide?

Others in GLP-1 agonists, side by side.

If you're weighing Semaglutide, it's worth reading Tirzepatide, Retatrutide, and Liraglutide in the same class.

YOU ARE HERE

Semaglutide

The drug in Ozempic and Wegovy: a weekly shot that curbs hunger for steady weight loss.

FDA-approved

Dose: 0.25 up to 2.4 mg per week (start low, increase slowly)
How often: Weekly

TIRZ

Tirzepatide

The drug in Mounjaro and Zepbound: a weekly shot for major weight loss and blood sugar.

FDA-approved

Dose: 2.5 up to 15 mg per week (start low, increase slowly)
How often: Weekly

RETA

Retatrutide

An experimental weekly shot with some of the biggest weight-loss numbers yet in trials.

Investigational

Dose: 1 up to 12 mg per dose (start low, increase slowly)
How often: Weekly

LIRA

Liraglutide

A daily version of the Ozempic-style shot for weight loss and blood sugar.

FDA-approved

Dose: 0.6 up to 3 mg per day (start low, increase slowly)
How often: Daily

See every GLP-1 drug side by side

See how this compares to 14 other GLP-1 drugs

Compared with

Cagrilintide vs Semaglutide

Both were tested in the same trial, in the same people, over the same 68 weeks. Semaglutide won on weight, and the combination beat both while coming in below their sum.

Read comparison →

Guides for this compound

How to Reconstitute a Peptide
Mix peptide powder with bacteriostatic water, step by step.
How to Read an Insulin Syringe
Read the units, convert to millilitres, and draw the exact dose.
mcg vs mg: The Peptide Dosing Mistake to Avoid
Your vial says mg and your protocol says mcg. Here is the conversion and how to check it.
Why Does My Peptide Injection Itch or Welt
Injection-site irritation, a histamine reaction, or a true allergy, and how to tell them apart.
Semaglutide vs Tirzepatide vs Retatrutide
One receptor, two, or three. Mechanism, trial weight loss, side effects, and real cost.

Sources

FDA, approval for MASH liver disease(2025)
FDA accelerated approval for MASH liver disease in adults with moderate to advanced scarring.
FDA, removal of the suicidal-ideation warning (Jan 2026)(2026)
FDA asked for the suicidal-ideation warning to be removed after a review found no increased risk.
NIH PMC, semaglutide and alcohol use disorder trial(2025)
Randomised trial reporting reduced alcohol craving and fewer heavy-drinking days.
STEP 1 trial, New England Journal of Medicine, 2021
STEP 1 analysis, PubMed Central

Last reviewed 14 August 2026

Beyond these, 500 records are indexed. Browse the records