Semaglutide Dosing Guide: Titration Schedule, mg-to-Units Math and GI Management

Semaglutide — a 31-amino-acid GLP-1 receptor agonist (MW 4,113.58 Da) with a half-life of roughly 165–184 hours — is dosed weekly by subcutaneous injection and follows a five-step titration ladder from 0.25 mg to 2.4 mg. Developed by Novo Nordisk and FDA-approved as Ozempic (2017), Rybelsus (2019), and Wegovy (2021), it produced a mean weight loss of 14.9% over 68 weeks in the STEP 1 trial (NEJM 2021, n=1,961). This guide covers the dosing schedule, the mg-to-units math for compounded vials, reconstitution, injection technique, and GI side-effect management.

For the direct conversion math, use the semaglutide dosing calculator; for reconstitution volume, use the reconstitution calculator alongside the BAC water calculator. Two distinct reader situations drive the content below: Wegovy/Ozempic pen users, for whom the pen is pre-metered and no unit conversion applies, and compounded-vial users, for whom concentration determines every draw.

What is the standard semaglutide dosing schedule?

The standard semaglutide weight-loss protocol starts at 0.25 mg injected subcutaneously once weekly for four weeks, then escalates every four weeks through a five-step ladder: 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg. The 2.4 mg weekly maintenance dose — which produced an average 14.9% weight loss over 68 weeks in the STEP 1 trial (Wilding et al., NEJM 2021, PMID 33567185) — is the FDA-approved Wegovy ceiling. Ozempic for type 2 diabetes uses a shorter ladder topping at 2.0 mg, and as of January 2026 the UK MHRA authorised a higher 7.2 mg weekly dose for adults with a BMI ≥30.

The four-week step interval comes directly from the STEP 1 titration protocol and exists for two reasons: it gives GLP-1 receptors time to downregulate after each dose escalation, and it mitigates the gastrointestinal side effects that intensify with every step. Skipping or shortening titration steps produces markedly higher nausea and vomiting rates without improving weight-loss outcomes, per the pivotal trials.

Wegovy (weight loss) vs Ozempic (diabetes) vs Rybelsus (oral) — same molecule, different ladders

All three formulations contain identical semaglutide; the ladders differ because the indications differ. Wegovy targets obesity management (2.4 mg maintenance), Ozempic targets glycemic control in type 2 diabetes (0.5–2.0 mg maintenance, dictated by glycemic response), and Rybelsus is the oral formulation for T2D, dosed daily rather than weekly due to ~1% oral bioavailability (3 → 7 → 14 mg daily). The 7.2 mg Wegovy dose, approved by the MHRA on 6 January 2026, was initially administered as three consecutive 2.4 mg injections; the MHRA approved a single-dose 7.2 mg pen on 14 April 2026. In the Phase 3b STEP UP trial, the 7.2 mg dose produced 20.7% mean weight loss over 72 weeks versus 17.5% at 2.4 mg.

Why the 4-week titration interval?

The 4-week spacing reflects two pharmacology constraints. GLP-1 receptor signaling shows tolerance — gastric emptying slows sharply with each dose step, and receptor desensitization typically stabilizes within 3–4 weeks, at which point further escalation is tolerated. Dropping to 2-week intervals, as some off-label compounded protocols propose, produces steeper GI side-effect curves without faster weight loss, because the rate-limiting step for fat loss is energy balance over time — not peak receptor occupancy.

What if I miss a dose of semaglutide?

If the missed dose is within 5 days of the scheduled injection, administer it as soon as possible and return to the regular weekly schedule. If more than 5 days have passed, skip the missed dose and resume at the next scheduled weekly injection. If two or more consecutive weeks are missed, the Wegovy label instructs prescribers to consider restarting at a lower dose to manage GI tolerability — GLP-1 receptor sensitivity increases during the washout, and re-initiating at the previous dose often produces severe nausea.

The Semaglutide Titration Ladder

How do I convert semaglutide mg to insulin-syringe units?

To convert a semaglutide dose in milligrams to insulin-syringe units, divide the dose in mg by the vial concentration in mg/mL, then multiply by 100: Units = (Dose in mg ÷ Concentration in mg/mL) × 100. On a U-100 insulin syringe, 1 mL equals 100 units, so a 0.25 mg dose from a 5 mg/mL vial is (0.25 ÷ 5) × 100 = 5 units. The conversion is purely geometric — units measure volume, not drug mass. Using a chart built for the wrong concentration is the single most common semaglutide dosing error and can deliver half or double the intended dose.

Conversion math applies only to compounded vials. Pre-filled Wegovy, Ozempic, and Rybelsus pens are metered by the manufacturer — you dial a dose on the pen, not a unit count on a syringe. For detailed worked examples across different vial concentrations, the how to calculate peptide doses guide walks through the underlying arithmetic.

The one formula that governs every conversion

Every unit conversion in a compounded-vial semaglutide protocol reduces to the same equation: Units = (Dose ÷ Concentration) × 100. Concentration is the critical input, and it is determined by two things — the total mg of semaglutide in the vial (printed on the label) and the volume of bacteriostatic water added during reconstitution. A 5 mg vial reconstituted with 1 mL of BAC water gives 5 mg/mL; the same 5 mg vial reconstituted with 2 mL gives 2.5 mg/mL. The drug mass is identical in both cases; only the draw volume changes.

Why the same "20 units" can mean different doses

The phrase "20 units of semaglutide" has no fixed meaning. At 5 mg/mL, 20 units (= 0.2 mL) delivers 1.0 mg. At 2.5 mg/mL, those same 20 units deliver 0.5 mg. At 10 mg/mL, they deliver 2.0 mg. This is why forum posts, TikTok videos, and older articles that give unit counts without specifying concentration are not usable reference material. Always check the vial label for concentration before drawing.

U-100 vs U-40 syringes — which to use

The U-100 insulin syringe (100 units per mL) is the standard in North America, the UK, and most of Europe, and is the default assumption in every compounded semaglutide chart. U-40 syringes (40 units per mL) still exist in some veterinary and legacy insulin markets — using a U-40 syringe with a chart built for U-100 delivers 2.5× the intended dose. Verify the "U-100" marking on the syringe barrel before drawing. Standard needle specifications for subcutaneous semaglutide are 30G or 31G at 4 mm to 8 mm length.

Pens vs vials: when conversion applies

Wegovy and Ozempic pens display dose in mg, not units, and are metered internally — the user dials to the prescribed dose and injects. No mg-to-unit conversion is required or appropriate. Conversion arithmetic applies only to compounded semaglutide delivered as a multi-dose vial, which the user reconstitutes and draws from with a separate insulin syringe.

Semaglutide mg to Units at Common Concentrations (U-100 insulin syringe)

Doses exceeding 100 units on a U-100 syringe require a larger-volume syringe or a split injection; the 1 mg/mL column has been capped where single-syringe draws become impractical.

How do I reconstitute a lyophilized semaglutide vial?

Reconstituting lyophilized semaglutide means adding bacteriostatic water to a powder vial to create an injectable solution. The chosen water volume sets the final concentration: a 5 mg vial plus 1 mL of BAC water gives 5 mg/mL, while the same vial plus 2 mL gives 2.5 mg/mL. Higher concentrations mean smaller injection volumes but less precision at microdose levels; lower concentrations give more accurate small draws but bigger injections. Wegovy and Ozempic pens ship pre-reconstituted, so this step applies only to compounded-vial users. For the underlying math, use the reconstitution calculator and the BAC water calculator; the step-by-step peptide reconstitution guide covers technique.

Reconstitution quality determines dose accuracy, product stability, and injection tolerability. A vial reconstituted with the wrong volume can deliver half or double the intended dose for months; a vial reconstituted with non-bacteriostatic diluent will degrade faster. Bacteriostatic water contains 0.9% benzyl alcohol, which suppresses microbial growth and enables multi-dose use over 28–30 days.

Step-by-step: reconstituting a 5 mg vial

Allow the vial and the BAC water to reach room temperature before starting — cold solutions sting more on injection and the lyophilized powder dissolves less evenly. Swab the rubber stopper of both the semaglutide vial and the BAC water vial with an alcohol wipe. Draw the chosen volume of BAC water into a 3 mL syringe, insert the needle into the semaglutide vial at a downward angle, and release the water slowly down the inside wall of the vial — not directly onto the lyophilized powder cake, which can cause foaming and partial denaturation. Do not shake; gently swirl or invert until the solution is completely clear. Full dissolution typically takes 60–120 seconds.

Choosing your BAC water volume

The volume you add determines everything downstream. More water = lower concentration = larger draws for a given mg dose, but better precision at microdose levels. Less water = higher concentration = smaller draws, but harder to measure accurately below 0.25 mg. For most maintenance-dose users, reconstituting a 5 mg vial with 1 mL to reach 5 mg/mL gives a clean one-syringe draw through the full 0.25 → 2.4 mg ladder. For microdose protocols or extended dose-hold strategies, reconstituting with 2 mL to reach 2.5 mg/mL gives more accurate small-volume draws at the cost of reaching the 48-unit draw at the 2.4 mg ceiling.

How long does reconstituted semaglutide last?

Once reconstituted with bacteriostatic water, semaglutide is stable under refrigeration (2–8 °C) for approximately 28–30 days, in line with the beyond-use dating standard for low-risk sterile compounding described in USP <797>. Keep the vial upright, protect it from light, and avoid repeated back-and-forth from refrigerator to room temperature — thermal cycling accelerates peptide degradation. The peptide storage guide covers stability in more depth.

What if my vial looks cloudy or has particles?

Reconstituted semaglutide should be clear and colorless. Cloudiness, suspended particles, or a visible precipitate indicates either incomplete reconstitution (swirl longer), a contaminated vial, or a degraded product. Do not inject a cloudy solution — discard it and, if the vial was recently purchased, flag the batch for the supplier. Persistent cloudiness across multiple vials from the same source is a quality-control red flag for that source.

Vial Size × Water Volume → Final Concentration

Where do I inject semaglutide, and why rotate sites?

Semaglutide is injected subcutaneously — into the fatty layer just beneath the skin — at three approved sites: the abdomen (avoiding a 5-cm circle around the navel), the front of the thigh, and the upper arm. Rotate sites week to week to prevent lipohypertrophy, the thickened or lumpy tissue that develops from repeated injections in the same spot and makes absorption unpredictable. Timing and site rarely affect efficacy, but site irritation and mild burning are common during the first few injections; the peptide injection technique guide and the subcutaneous vs intramuscular comparison cover technique in depth.

The three approved injection sites

Per the Wegovy and Ozempic prescribing information, approved sites are the abdomen (not within 5 cm of the navel, to avoid umbilical vasculature), the anterior or lateral thigh, and the posterior upper arm. All three sites have adequate subcutaneous fat depth in most adults for a 4–8 mm, 30G–31G needle to deposit semaglutide in the hypodermis. Intramuscular injection is not recommended — absorption kinetics change, and the extended-release profile that drives weekly dosing assumes SC pharmacokinetics.

How to rotate sites

A practical weekly rotation: Week 1 abdomen-left, Week 2 abdomen-right, Week 3 thigh-left, Week 4 thigh-right, Week 5 arm-left, Week 6 arm-right, then repeat. Within each site, shift by at least 2.5 cm from the previous injection. The goal is that no single square centimeter of skin receives more than one injection per 6-week cycle — enough time for any local inflammation or microfibrosis to fully resolve before re-use.

Why does semaglutide burn when injected?

Three causes account for most injection-site burning. First, cold solution — injecting a vial straight from the refrigerator stings; let it warm 10–15 minutes at room temperature. Second, benzyl alcohol in bacteriostatic water used for compounded vials has a mild local irritant effect some users notice. Third, superficial injection — depositing into the dermis rather than the subcutaneous fat layer burns sharply and absorbs unreliably. If burning persists with a Wegovy or Ozempic pen despite proper technique, contact the pharmacy — pH drift or degradation in a mishandled pen is possible.

Needle gauge and length

Most subcutaneous semaglutide injections are performed with a 30G or 31G needle at 4 mm to 8 mm length. Thinner gauges (31G) reduce injection pain marginally. Shorter needles (4–6 mm) suffice for abdominal injection in most body compositions; 6–8 mm is typical for thigh injection where subcutaneous depth varies. Needle re-use is not recommended — the silicone coating degrades after one use, dulling the tip and increasing pain and risk of lipohypertrophy.

What are the side effects of semaglutide — and how long do they last?

The most common semaglutide side effects are gastrointestinal: nausea (44.2% of Wegovy users in STEP 1), diarrhea (31.5%), vomiting (24.8%), constipation (23.4%), and abdominal pain (20.4%). Individual nausea bouts have a median duration of about 8 days, and population-level nausea drops sharply after week 20 of treatment as receptor tolerance develops. Most GI effects are mild to moderate and concentrate around dose escalations. Serious but rare risks include pancreatitis, gallbladder disease (~2.6% in STEP 1), and — per the FDA boxed warning — thyroid C-cell tumors in rodent studies (human relevance unknown). The semaglutide science and safety deep-dive covers the mechanism behind these effects, and the sibling tirzepatide side-effects article documents a parallel GLP-1 profile.

GI side effects dominate the safety picture because GLP-1 receptors in the vagal afferent pathway and area postrema mediate both appetite suppression (the therapeutic effect) and nausea signaling (the side effect). Research from Dr. Daniel Drucker and colleagues at the University of Toronto established this shared mechanism — which is why a "nausea-free high-efficacy GLP-1" remains an unresolved drug-design challenge.

Semaglutide Side-Effect Profile from STEP 1 (Wegovy, 2.4 mg)

How do I manage semaglutide nausea and GI side effects?

Semaglutide nausea is best managed through meal strategy and hydration rather than medication. Most clinicians recommend small meals (200–300 calories), stopping at first fullness, avoiding high-fat and fried foods (which compound the delayed gastric emptying), staying upright for 30+ minutes after eating, and maintaining steady fluid intake throughout the day. If nausea remains severe at an escalation step, holding the current dose for an additional 4 weeks — rather than stepping up on schedule — is the standard clinical workaround. Prescription antiemetics (ondansetron) are an option when lifestyle measures fail, under physician guidance.

The nausea timeline is predictable: incidence peaks in days 1–3 after each dose escalation, plateaus within 4–8 weeks at the new steady state, and drops substantially across the population after week 20 as receptor-level tolerance develops. For individuals struggling through titration, recognizing this curve reduces the temptation to abandon treatment during what is typically the worst GI phase.

The meal strategy that matters most

Three dietary changes produce the largest nausea reduction in clinical practice: portion control (stop at first fullness, not at plate completion), low-fat macronutrient composition (fat slows gastric emptying additively with semaglutide, amplifying nausea), and protein + fiber prioritization at the start of meals. Greasy, fried, and very rich foods are the most common trigger — many users discover this by accident during Week 2 of an escalation step. Smaller, more frequent meals (4–5 × 200–300 kcal) are generally tolerated better than 2–3 large meals.

Hydration: the most underrated intervention

Dehydration amplifies nausea and is the proximate cause of most semaglutide-associated acute kidney injury cases. The appetite-suppressant effect reduces thirst drive alongside hunger, so users often drink less without noticing. Target 2–3 L of fluid daily, mostly water, and front-load hydration in the 24 hours before each escalation injection.

When to hold your dose instead of stepping up

If GI side effects at an escalation step are severe enough to disrupt eating or daily function, the standard clinical approach is to hold at the current dose for an additional 4 weeks before attempting the next step. This extends the titration timeline but markedly improves tolerability. Community-reported "microdosing" protocols — weekly doses below the 0.25 mg initiation level — operate on the same logic but without RCT support; they are a tolerance strategy, not an efficacy strategy.

Red flags — when to stop the drug and call a doctor

Four symptom patterns warrant immediate medical evaluation: persistent severe abdominal pain radiating to the back (possible pancreatitis), vomiting that prevents fluid intake for more than 24 hours (dehydration and possible AKI risk), right upper quadrant pain with nausea or yellowing of skin or eyes (possible gallbladder disease), and unexplained neck swelling or hoarseness (per the FDA boxed warning on thyroid C-cell tumors, relevant primarily in patients with personal or family history of medullary thyroid carcinoma or MEN 2 syndrome). Any of these symptoms is a reason to stop the drug and seek evaluation, not to push through.

How do I know the semaglutide I bought is authentic?

Authenticity verification depends on source. Pen formulations (Wegovy, Ozempic, Rybelsus) purchased from licensed pharmacies carry Novo Nordisk holographic seals, batch-matched NDC numbers, and tamper-evident packaging — the FDA counterfeit Ozempic warning from November 2023 details the specific visual red flags on counterfeit pens found in the US supply chain. Compounded semaglutide — whether from 503A pharmacies or research-use channels — requires buyer-side verification: an HPLC purity certificate showing ≥98% purity for the semaglutide peak, mass spectrometry confirming the 4,113.58 Da molecular weight, and a certificate of analysis from a named third-party lab. The where to buy semaglutide purity and identity checks guide walks through the specific checks for this compound.

Peptigrity's independent lab-test database surfaces HPLC and MS results for semaglutide samples tested across multiple sources, and the how to test peptides hub explains how buyers can submit their own samples. For interpreting the certificates themselves, the guide to reading peptide lab test results covers HPLC chromatogram reading and MS molecular weight confirmation, and the red flags in peptide CoAs guide lists the specific patterns that indicate forged or low-integrity documentation.

Four red flags in a compounded-vial purchase warrant rejection: no CoA supplied, CoA from an unnamed or non-verifiable lab, reported purity below 98% for the semaglutide peak, and lot numbers on the vial that don't match the lot number on the CoA. A CoA without cross-matchable batch identifiers is not a CoA — it's marketing collateral.

How does semaglutide dosing compare to tirzepatide and other GLP-1s?

Semaglutide and tirzepatide are the two dominant weekly GLP-1 options, with meaningful dosing-math differences. Semaglutide tops at 2.4 mg weekly (Wegovy) and produced 14.9% mean weight loss in STEP 1; tirzepatide tops at 15 mg weekly (Zepbound) and produced 20.9% mean weight loss at the 15 mg dose in SURMOUNT-1 (Jastreboff et al., NEJM 2022, PMID 35658024), with the dual GIP/GLP-1 mechanism credited for the higher ceiling. Retatrutide, a Phase 3 triple GIP/GLP-1/glucagon agonist, has shown ~24% weight loss in Phase 2 data. Dose frequency is identical across all three (weekly subcutaneous); the practical differences are the number of titration steps and the side-effect trajectory.

For readers weighing semaglutide against tirzepatide specifically, the existing semaglutide vs tirzepatide comparison covers efficacy and safety side by side, and the paired tirzepatide dosing guide walks through the tirzepatide titration ladder and unit math. The retatrutide vs tirzepatide vs semaglutide comparison addresses the three-way decision for readers evaluating the full GLP-1 spectrum. For dose-by-dose cost comparison across the three compounds, the cost-per-dose calculator accepts vial price, concentration, and weekly dose as inputs.

Weekly GLP-1 Dosing at a Glance

Semaglutide remains the more widely studied option — the SELECT trial (NEJM 2023) established cardiovascular outcome benefit in overweight and obese non-diabetics, a result tirzepatide has not yet demonstrated in a completed outcome trial.

Frequently Asked Questions

What is microdose semaglutide?

Microdosing means using doses below the 0.25 mg weekly initiation dose — typically 0.05 to 0.125 mg weekly. It is a community practice, not an FDA-approved protocol, with no RCT evidence supporting efficacy at sub-therapeutic levels. Users adopt it to reduce GI side effects during initiation, maintain weight loss on a lower ceiling, or extend vial economics. The approach has no trial-grade data behind it and should be framed as a tolerance strategy rather than a proven alternative to the STEP 1 ladder.

How many units is 2.4 mg of semaglutide?

The answer depends entirely on the vial concentration. At 5 mg/mL (5 mg vial + 1 mL BAC water), 2.4 mg = 48 units on a U-100 syringe. At 2.5 mg/mL, 2.4 mg = 96 units. At 10 mg/mL, 2.4 mg = 24 units. The unit conversion chart in the preceding section covers every common concentration, and the semaglutide calculator handles the math directly for any vial configuration.

What happens if I miss a week of semaglutide?

If the missed dose is within 5 days of the scheduled injection, inject as soon as remembered and resume the regular weekly schedule. If more than 5 days have passed, skip the dose and inject at the next scheduled time. If two or more consecutive weeks are missed, the Wegovy label recommends considering a dose reduction on restart — GLP-1 receptor sensitivity recovers during washout, and resuming at the previous maintenance dose often produces severe rebound nausea.

Does semaglutide need to be refrigerated?

Unopened pens and vials: yes, 2–8 °C until the in-use period begins. Once an Ozempic or Wegovy pen is in active use, most prescribing information allows room-temperature storage (up to 30 °C) for up to 28–56 days depending on the specific product. Reconstituted compounded vials: refrigerate, with a typical beyond-use date of 28–30 days under USP <797> low-risk compounding standards. The assigned BUD for any specific compounded product should come from the dispensing pharmacy.

Can I switch from Wegovy/Ozempic pens to compounded vials?

The active molecule is identical, but there is no trial-grade bioequivalence data for compounded formulations against the FDA-approved pens — compounded vial concentrations vary by pharmacy, so dose math is not transferable between the two. A patient on Wegovy 1.0 mg weekly cannot simply draw "1.0 mg" from a compounded vial without knowing the vial's specific mg/mL concentration and running the unit conversion. Any transition should be done under prescriber supervision with explicit dose recalculation.

How long until semaglutide suppresses appetite?

Some appetite reduction appears within 1 to 2 weeks from acute GLP-1 receptor activation, but the full effect emerges over 8 to 12 weeks as the dose escalates and plasma semaglutide reaches steady state (typically 4–5 weeks per dose-step at the given half-life of ~7 days). Users often report a noticeable step-change in hunger at each escalation, followed by a plateau within 2–3 weeks at the new dose.

Why does semaglutide burn when injected?

Three common causes: cold injection — warm the vial or pen 10–15 minutes at room temperature before use; benzyl alcohol in bacteriostatic water used for compounded formulations — some users are more sensitive than others; and injection too shallow into the dermis rather than the subcutaneous fat layer. Persistent burning with an approved pen despite correct technique is worth reporting to the dispensing pharmacy, as it can indicate a degraded or mishandled product.

This article is for educational and informational purposes only and does not constitute medical advice. Semaglutide is an FDA-approved prescription medication; compounded semaglutide is not an FDA-approved formulation and is subject to ongoing regulatory review. Always consult a qualified healthcare provider before starting, changing, or stopping semaglutide or any peptide. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.