One injection a week
Not a daily medication. Same day each week, with or without food, at whatever time fits.
The engineered half-life is roughly seven days, which is what makes weekly dosing possible at all.
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Semaglutide Injection
Once-Weekly GLP-1 for Weight Management
Metabolic
A once-weekly GLP-1 injection for weight management, compounded with B12 and titrated by your provider.
- Reduced appetite and less preoccupation with food
- Feeling full earlier and for longer after meals
- A single once-weekly injection rather than daily dosing
- A dose your provider raises gradually to limit side effects
- Vitamin B12 compounded into the same vial
Dosage1 mL vial compounded with B12; strength set by your provider
AdministrationSubcutaneous injection, once weekly
Compounded in the U.S.A.
About
What is Semaglutide?
Semaglutide is a GLP-1 receptor agonist. GLP-1 is an incretin — a hormone your small intestine releases after you eat, which tells the pancreas to release insulin, tells the stomach to empty more slowly, and tells the brain you have had enough. The molecule is a modified version of that hormone, engineered to survive in the body for about a week rather than a few minutes.
That week-long half-life is the whole reason it is a once-weekly injection. It is also why the dose has to be raised gradually: your gut adapts to the slowed emptying over time, and moving up faster than that adaptation is what produces the nausea the medication is known for. The titration schedule is not caution for its own sake — it is the difference between a medication people stay on and one they quit in month two.
PeRx compounds semaglutide with vitamin B12 in a single vial. Your provider sets the concentration, reviews how you are doing before every refill, and raises it when you are ready rather than on a fixed calendar. If a step is difficult, they can hold you there or step back down.
This is a compounded preparation, not one of the FDA-approved branded products. It is prescribed for you specifically by a licensed provider and compounded by an FDA-registered 503A pharmacy. Syringes, alcohol swabs, and a step-by-step injection guide arrive in the box.
Why people explore Semaglutide
A clearer path forward.
Your provider owns the dose
Every refill goes back to a provider who sees how you are doing before deciding whether to move you up.
You cannot buy a higher strength yourself. The dose changes when a clinician decides it should.
Hunger gets quieter, not forbidden
The mechanism acts on appetite signalling rather than willpower — most people describe food taking up less mental space.
GLP-1 receptors sit in the hypothalamus and brainstem, which is why the effect feels like reduced interest rather than suppressed craving.
B12 in the same vial
Compounded with vitamin B12, so it is one injection rather than two.
Glycine is available as an alternative base if B12 does not suit you.
What it helps with
Designed for these concerns.
- Reduced appetite and less preoccupation with food
- Feeling full earlier and for longer after meals
- A single once-weekly injection rather than daily dosing
- A dose your provider raises gradually to limit side effects
- Vitamin B12 compounded into the same vial
- Ongoing provider review before every refill
Ideal for
Adults pursuing medically supervised weight management · People who want a once-weekly option rather than a daily medication · Anyone who wants a provider reviewing their dose before each refill
The science
How Semaglutide works.
Semaglutide binds the GLP-1 receptor, mimicking the incretin hormone the small intestine releases in response to food. That signal acts on appetite centres in the hypothalamus to reduce hunger and food preoccupation, slows gastric emptying so meals stay satisfying for longer, and increases glucose-dependent insulin release. Because it is glucose-dependent, the insulin effect scales with blood sugar rather than acting continuously.
01
Signal
Semaglutide is delivered by subcutaneous injection, once weekly, entering circulation and reaching the tissues where it acts.
02
Cellular response
Semaglutide binds the GLP-1 receptor, mimicking the incretin hormone the small intestine releases in response to food. That signal acts on appetite centres in the hypothalamus to reduce hunger and food preoccupation, slows gastric emptying so meals stay satisfying for longer, and increases glucose-dependent insulin release. Because it is glucose-dependent, the insulin effect scales with blood sugar rather than acting continuously.
03
Outcome
Over the following weeks, most people report gradual change in the areas Semaglutide targets: medically supervised weight management.
Subcutaneous injection, once weeklyCompounded in the U.S.A. at a 503A pharmacyProvider-prescribed
What the research shows
Backed by published science.
- GLP-1 receptor agonists are among the most extensively studied drug classes in metabolic medicine
- The incretin effect they mimic was first described in the 1960s
- Dose escalation over several months is standard, and exists specifically to limit gastrointestinal side effects
- Gastrointestinal effects are the most commonly reported, and typically ease as the body adjusts to each step
Lab tested medications
for quality & potency
Our medication is delivered from a state-licensed pharmacy in our network, right to your door when you need it.
Third-party quality control testing
Compounded in U.S. pharmacies
Lab tested for quality & potency
Our pharmacies perform third-party testing through FDA and DEA registered labs to run quality control checks for every compounded lot. They test four key characteristics associated with quality and safety.
Potency Test
PassedPerformed on every batch to confirm the active ingredient is present at the labeled concentration. Your vial contains exactly what it should.
Sterility Test
PassedTests for the presence of bacteria, fungi, and other microorganisms. Every batch is tested and must meet the requirements of USP 797.1.
Endotoxin Test
PassedScreens for bacterial endotoxins that can cause fever or adverse reactions. Every batch is tested and must not exceed the threshold limits defined in USP 85.
pH Test
PassedAssesses the acid/base balance to ensure minimal irritation upon injection and confirm the solution is within the correct range for subcutaneous administration.
What to expect
Your Semaglutide timeline.
- 01
Week 1–4
Starting dose
What you may notice: Appetite changes are often noticeable within the first week or two. Mild nausea, fullness arriving sooner than expected, and constipation are the common early effects.
What’s happening: You start at the lowest concentration. This step is about tolerance, not results — it exists so your gut adapts to slowed gastric emptying before the dose goes up.
- 02
Month 2–4
Stepping up
What you may notice: Each increase can bring a few days of the early side effects back. They typically settle within the week.
What’s happening: Your provider raises the concentration one step at a time, checking your check-in answers before each move. Some people stay at a middle step; there is no requirement to reach the top.
- 03
Month 5 onward
Maintenance
What you may notice: Most people settle at a dose that balances effect against how they feel day to day.
What’s happening: The dose stops climbing and refills continue at whatever concentration you and your provider settled on. Check-ins keep happening every cycle.
What’s included
Everything you need to start safely.
From the moment you finish your assessment to your first dose, every step is handled by licensed providers and U.S. pharmacies.
New to self-injection? See the step-by-step guide- Provider evaluation and prescription
- One month of medication, compounded with B12
- Insulin syringes and alcohol swabs
- Step-by-step injection guide
- Free overnight shipping, cold-chain packed
- A provider review before every refill
- Pause, skip, or cancel any time from your account
FAQ
Common questions about Semaglutide.
Patient reviews
What patients are saying.
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This is not medical advice. Every patient's experience differs and not everyone qualifies for peptide therapy. All reviews are from verified PeRx patients and are published as submitted. Peptide therapy requires a valid prescription from a licensed provider.
Your safety, first
Important safety information.
- Not for anyone with a personal or family history of medullary thyroid carcinoma or MEN 2
- Not for use during pregnancy, while breastfeeding, or if planning pregnancy within 6 months
- Discuss any history of pancreatitis, gallbladder disease, or gastroparesis with your provider
- Tell your provider if you take insulin or a sulfonylurea — the dose may need adjusting
- Nausea, vomiting, diarrhoea, and constipation are common, especially after a dose increase
- Seek care for severe abdominal pain, particularly pain that spreads to your back
- Requires licensed provider supervision
All prescriptions are issued by a licensed US provider after reviewing your intake.
Side effects, contraindications, and what to discuss with your provider before starting.
Read safety informationSupporting research
Selected studies.
A selection of peer-reviewed work on Semaglutide. Browse the full literature on PubMed and Google Scholar for ongoing research.
The incretin system and GLP-1 physiology
Drucker DJ. Cell Metab. 2018;27(4):740–756.Gastric emptying and the GLP-1 receptor agonist class
Nauck MA, Meier JJ. Diabetes Obes Metab. 2019;21(S1):5–21.Dose escalation strategies to limit gastrointestinal effects
Wharton S et al. Diabetes Obes Metab. 2022;24(1):94–105.
The statements on this page have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The FDA does not review or approve compounded medications for safety or effectiveness. Off-label use must be prescribed and supervised by a licensed provider.
Last updated April 2026
Medical disclaimer
The information provided on this page is for educational purposes only and is not intended as medical advice, diagnosis, or treatment. Peptide therapy requires a valid prescription from a licensed healthcare provider. Individual results may vary. No specific outcomes are guaranteed.
The peptides on this site are not FDA-approved. They are compounded by licensed pharmacies under provider supervision. Certain peptides are prohibited by WADA and major sports organizations. Statements on this page have not been evaluated by the FDA. These products are not intended to diagnose, treat, cure, or prevent any disease.
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