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№ 009

Semaglutide

The original weight-loss wave, sold as Ozempic / Wegovy. A GLP-1 agonist.

Fat Loss
Evidence: Strong

Semaglutide: The original weight-loss wave, sold as Ozempic / Wegovy. A GLP-1 agonist. Semaglutide is the first wave of modern weight-loss drugs, sold as Ozempic and Wegovy.

FDA ⓘ
Approved
WADA
Not banned
Typical dose
Start 0.25mg weekly
Half-life ⓘ
~7 days
Route ⓘ
Subcutaneous
Schedule
Once weekly
In plain English

Semaglutide is the first wave of modern weight-loss drugs, sold as Ozempic and Wegovy. Single-receptor version of Tirzepatide. Slightly less effective and slightly rougher side effects, but well-studied and widely available.

Status & legalityWhat do these mean? →
Natty? ⓘ
Not natty
FDA ⓘ
Approved

Approved as Ozempic (2017, type 2 diabetes), Rybelsus (2019, oral), and Wegovy (2021, obesity).

Compounding ⓘ
Approved drug

Available as an FDA-approved drug, not a compounded peptide.

WADA ⓘ
Not listed
Prescribed ⓘ

Yes, extremely widely prescribed. Insurance coverage variable for weight-loss indication.

Before you start

Wear a CGM the first 14 days.

Same as tirz. A two-week sensor (~$80, OTC, no prescription) tells you more about how YOUR body is responding to Semaglutide than any protocol guide can. Most users wear one and don't again. The first cycle is the one that matters.

Get a CGM →

Who it's for

  • →Beginners to GLP-class peptides
  • →Users with insurance coverage on Wegovy / Ozempic
  • →Metabolic-syndrome adults under provider guidance

What to expect

  1. Week 1

    Appetite drops. Nausea variable.

  2. Week 4

    First titration. 2-4lb down typically.

  3. Week 8

    5-8lb cumulative for most.

Looking at Semaglutide? Your next 3 steps

  1. 1Work out your exact dose

    Vial size + BAC water turns into the exact units to draw for Semaglutide.

    Open calculator →
  2. 2See what to stack & monitor

    The companion supplements and the bloodwork worth tracking on this kind of protocol.

    Bloodwork guide →
  3. 3Save it & ask the Coach

    A free account saves your stack; membership adds the stack-aware AI Coach.

    Create free account →

How it works (mechanism)

GLP-1 receptor agonist resistant to DPP-4 enzymatic breakdown. Binds GLP-1 receptors in the brain (satiety), gut (delayed gastric emptying), and pancreas (glucose-dependent insulin secretion). Weekly dosing achieves steady-state GLP-1 signaling.

Dosing protocol

Members only

Stacks well with

Members only

Stack essentials

Members only

Side effects

01Nausea (often more than tirzepatide)
02Constipation
03Fatigue
04Sulfur burps

When NOT to use

  • ⚠MTC / MEN-2 history
  • ⚠Pancreatitis history
  • ⚠Pregnancy / nursing

Bloodwork to monitor

  • • Lipid panel
  • • ALT/AST
  • • A1C

Common mistakes

  • • Titrating too fast
  • • Skipping protein and lifting
  • • Treating it as a forever drug with no plan

Drug & supplement interactions

  • ⚠Insulin and sulfonylureas: dose reduction usually needed to prevent hypoglycemia
  • ⚠Slows gastric emptying, affects oral medication absorption (especially time-sensitive drugs like contraceptives)
  • ⚠Warfarin: monitor INR more closely after starting
  • ⚠Avoid alcohol during titration steps (worsens nausea)

The Pepdex take

Aggressive muscle loss is the most under-discussed side effect of running Semaglutide aggressively. Not technically a side effect, a feature of how rapid the weight loss is when you're not eating enough protein or lifting heavy. Plenty of users drop 30 lbs and somehow look worse in the mirror. Lift heavy 3x/week, hit 0.8-1g protein per lb of bodyweight, or expect skinny-fat results. If those aren't on the table, run Tirz at a lower dose instead.

Community patterns

Members only
Free, no account needed

New to Semaglutide? Grab the starter checklist.

Drop your email and we'll send the one-page first-cycle starter checklist, plus a heads-up if Semaglutide changes legal status. No account needed.

No spam. No selling your email. Just the checklist and the occasional reclassification alert.

AI Coach, live sample
Members only
is 250mcg of bpc enough for a knee injury?
For a knee, 250 mcg sub-q daily is the standard working dose and a solid place to start. The trick with BPC is consistency, give it weeks, not days. Inject close to the joint, run it 4-6 weeks, and don't drop below 200 mcg, it tends to stop cracking the threshold reliably down there. If it hasn't moved at all by week 3, that's when adding TB-500 earns its place.
how much bac water for a 10mg reta vial?
3 mL is the standard play for a 10 mg reta vial. That's 3,333 mcg/mL, clean unit math across the titration: 2 mg = 60 units, 4 mg = 120 units, 6 mg = 180 units on a 100-unit insulin syringe. Run 2 mL instead if you want fewer, more concentrated shots (5,000 mcg/mL, so 2 mg = 40 units). Since most people titrate up over ~12 weeks, 3 mL keeps the numbers cleanest.
what should i track on bloodwork for tirzepatide?
Lipid panel, ALT/AST (liver enzymes), and an A1C, baseline before you start then every 3 months. If you've got metabolic-syndrome history, add fasting glucose and insulin so you can actually watch insulin sensitivity improve. You don't need a big hormone panel for a GLP-1.

Ask the Coach anything about Semaglutide or your own stack. This is it working.

Trained only on Pepdex content. Does the dose math, flags interactions, knows your stack. Won't push vendors, won't pretend to be a doctor.

Get the Coach, $7.99/mo →

Frequently asked

What is Semaglutide?+
Semaglutide is the first wave of modern weight-loss drugs, sold as Ozempic and Wegovy. Single-receptor version of Tirzepatide. Slightly less effective and slightly rougher side effects, but well-studied and widely available.
Is Semaglutide FDA approved?+
Approved as Ozempic (2017, type 2 diabetes), Rybelsus (2019, oral), and Wegovy (2021, obesity).
Is Semaglutide legal?+
Semaglutide is FDA-approved and legal to obtain by prescription in the US. Yes, extremely widely prescribed. Insurance coverage variable for weight-loss indication.
Is Semaglutide banned by WADA?+
Semaglutide is not currently on the WADA prohibited list.
Are you still natty after taking Semaglutide?+
No. Semaglutide is a performance-enhancing peptide and would disqualify a strict natty claim.
Do doctors prescribe Semaglutide?+
Yes, extremely widely prescribed. Insurance coverage variable for weight-loss indication.
What's the typical dose of Semaglutide?+
Start 0.25mg weekly. Titrate every 4 weeks. Common max 2.4mg.
What are the side effects of Semaglutide?+
Common side effects include: Nausea (often more than tirzepatide); Constipation; Fatigue; Sulfur burps. Less common effects and full safety details are on the entry page.
How long until Semaglutide starts working?+
Appetite drops. Nausea variable.
What can you stack with Semaglutide?+
Common pairings: Standalone. Full stacking protocol and timing on the entry page.
Where do people get Semaglutide?+
Semaglutide is dispensed through licensed pharmacies with a prescription. Some compounding pharmacies and telehealth services prescribe it. Pepdex is not a vendor or pharmacy. See /coa for how to verify Certificate of Analysis on any supplier.
Semaglutide vs Tirzepatide, which is better?+
Which is more effective for weight loss, Tirzepatide (Mounjaro / Zepbound) or Semaglutide (Ozempic / Wegovy)? Side-by-side on dose, mechanism, side effects, FDA status. Full head-to-head comparison: https://pepdex.co/compare/tirzepatide-vs-semaglutide
Semaglutide vs Cagrilintide, which is better?+
Semaglutide vs Cagrilintide: different appetite pathways and why CagriSema (the combo) is being studied. Full head-to-head comparison: https://pepdex.co/compare/semaglutide-vs-cagrilintide
Semaglutide vs Retatrutide, which is better?+
Semaglutide vs Retatrutide: first-gen GLP-1 vs the new triple agonist (GLP-1 + GIP + glucagon). Effect size, side effects, availability. Full head-to-head comparison: https://pepdex.co/compare/semaglutide-vs-retatrutide

Head-to-head with Semaglutide

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Semaglutide vs Tirzepatide →
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Semaglutide vs Cagrilintide →
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Semaglutide vs Retatrutide →
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More in Fat Loss

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Tirzepatide

Strong weight loss with a cleaner side effect profile than semaglutide. A dual agonist (GLP-1 + GIP), FDA-approved as Mounjaro / Zepbound.

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Retatrutide

Triple agonist (GLP-1 + GIP + glucagon) from Eli Lilly. In trials it outperforms Tirzepatide for weight loss.

№ 058
Liraglutide (Saxenda / Victoza)

Daily GLP-1 receptor agonist. FDA-approved 2010 (Victoza, T2D) and 2014 (Saxenda, obesity). The first wave of modern GLP-1 weight-loss therapy and direct predecessor to Semaglutide.

№ 022
Cagrilintide

An appetite-control shot for weight loss. A long-acting amylin agonist that works on a different pathway than the GLP-1 drugs, often paired with Semaglutide as 'CagriSema' to break GLP-1 plateaus.