Semaglutide reconstitution calculator

Enter your vial amount and target dose. DrawDose returns the BAC water volume, syringe units, and a vial label you can copy.

Three FDA-approved brands, one molecule

Semaglutide is the active ingredient in three FDA-approved Novo Nordisk products: Ozempic (subcutaneous, type 2 diabetes), Wegovy (subcutaneous, chronic weight management), and Rybelsus (oral, type 2 diabetes). The molecule is the same across all three; the formulations and titration targets differ.

Ozempic and Wegovy are subcutaneous injections that share the same per-mg dosing math but reach different maintenance targets. Per the Ozempic prescribing information, the maintenance dose for type 2 diabetes is 1 mg or 2 mg once weekly. Per the Wegovy prescribing information, the maintenance dose for chronic weight management is 2.4 mg once weekly.

Rybelsus is a daily oral tablet (3 mg, 7 mg, or 14 mg). It uses the same molecule but with an absorption enhancer (SNAC) for oral bioavailability. Reconstitution math does not apply to Rybelsus. This page covers the subcutaneous forms.

Compounded semaglutide is the same molecule prepared by compounding pharmacies and sold in multi-dose lyophilized vials. Per FDA guidance, compounded semaglutide is not FDA-approved as a finished drug product; the molecule is the same as in branded Ozempic and Wegovy, but the formulation, concentration, and quality controls vary by compounder.

Quick answer for the most common vial sizes

The 1 mL : 1 mg ratio documented across compounding pharmacy formulation guides for semaglutide produces a clean 1 mg/mL concentration where every 25 units delivers 0.25 mg.

The 1:1 ratio (1 mg/mL) puts the early titration steps on clean unit numbers. The 2.5 mg/mL ratio is preferred when the protocol targets the higher Wegovy-style maintenance dose of 2.4 mg, since 240 units exceeds a 1 mL insulin syringe capacity at the dilute ratio. DrawDose accepts any vial size and any BAC water volume and returns the correct syringe draw for the dose entered.

How to reconstitute lyophilized semaglutide

The procedure follows the standard sterile-injection prep workflow documented in compounding pharmacy formulation guides and peptide stability literature. Compounded semaglutide vials ship lyophilized; branded Ozempic and Wegovy ship as pre-filled solution pens that do not require reconstitution.

Bring the vial and BAC water to room temperature for 15 to 20 minutes before mixing. Cold liquid hitting cold powder slows dissolution and increases the chance of clumping. Wipe both vial tops with an alcohol swab and let them dry. Draw the BAC water into a 1 mL syringe.

Insert the needle into the semaglutide vial at an angle so the water runs down the inside wall, not directly onto the powder pellet. Direct impingement on lyophilized peptide generates foam and can affect peptide structure. Once the water is in, swirl the vial gently for 20 to 30 seconds. Do not shake. Semaglutide dissolves clearly when properly reconstituted; cloudiness or particulate that does not clear within a minute indicates a sourcing concern.

Why concentration determines syringe units, not vial size

The relationship between vial size, BAC water, and syringe draw is fixed by concentration math. A 5 mg vial with 5 mL of water gives 1 mg/mL — every 25 units delivers 0.25 mg. The same 5 mg vial with 2 mL of water gives 2.5 mg/mL, where 25 units delivers 0.625 mg. To hit a 0.25 mg target dose with the second mix, the draw is 10 units instead of 25.

Standard reconstitution practice keeps the draw between 10 and 100 units on a 1 mL insulin syringe. For Ozempic-target protocols (max 2 mg) the 1 mg/mL ratio works across the full titration. For Wegovy-target protocols (max 2.4 mg) a 2.5 mg/mL ratio is preferred because 2.4 mg at 1 mg/mL would require a 240-unit draw, which exceeds the syringe capacity. DrawDose computes this automatically; the auto-selected BAC water volume on the result panel is tuned to keep the draw in a measurable band for the target dose.

FDA-approved titration schedules

Per the Wegovy and Ozempic prescribing information published by Novo Nordisk, semaglutide is administered as a once-weekly subcutaneous injection. Both labels specify a titration with each step lasting at least four weeks before increasing.

The Wegovy titration for chronic weight management runs as follows:

Weeks 1 to 4: 0.25 mg once weekly. Per the prescribing information, this is a starting dose for treatment initiation, not for weight management efficacy.

Weeks 5 to 8: 0.5 mg once weekly.

Weeks 9 to 12: 1.0 mg once weekly.

Weeks 13 to 16: 1.7 mg once weekly.

Weeks 17 onward: 2.4 mg once weekly. Per the label, this is the maintenance dose with documented efficacy from the STEP trials referenced in the prescribing information.

The Ozempic titration for type 2 diabetes uses the same starting dose and early steps but lower maintenance targets:

Weeks 1 to 4: 0.25 mg once weekly.

Weeks 5 onward: 0.5 mg once weekly. Per the Ozempic label, this is sufficient for many patients.

If glycemic control is inadequate, escalation to 1 mg once weekly is documented after at least four weeks at 0.5 mg, and to 2 mg once weekly after at least four weeks at 1 mg. The 2 mg maintenance dose is the maximum approved Ozempic dose.

The half-life of semaglutide is approximately 7 days per the prescribing information, which enables the once-weekly dosing schedule. Steady state plasma concentration is reached after 4 to 5 weeks of consistent weekly dosing.

The label specifies that if a patient does not tolerate a dose increase, the manufacturer recommends returning to the previous tolerated dose.

Community protocols: slow titration and microdosing

Survey data aggregated from r/Semaglutide, r/CompoundedSemaglutide, and r/Ozempic, alongside compounded-pharmacy protocol literature, describes two titration patterns common in compounded-vial practice that deviate from the FDA-approved schedule.

Slow titration extends each step from the label's 4 weeks to 6 or 8 weeks. The pattern is documented among users with persistent gastrointestinal effects. Reaching the 2.4 mg Wegovy maintenance dose takes 25 to 33 weeks instead of the 17 weeks the label specifies. Many users in survey data hold long-term at 1.0 or 1.7 mg rather than escalating to the maximum.

Microdosing starts below 0.25 mg, often at 0.125 mg or lower, with step-ups over additional weeks before joining the standard 0.25 mg starting line. There is no published clinical trial data on semaglutide doses below 0.25 mg subcutaneously. Some compounded pharmacies offer sub-0.25 mg formulations and prescribers use them off-label for users sensitive to gastrointestinal effects. The honest framing is that the safety and efficacy profile of doses below 0.25 mg is unknown rather than known-safe.

A separate community pattern is target switching — starting on the Ozempic-style schedule (max 2 mg), reaching tolerance, and either continuing at that dose or switching to the Wegovy schedule for weight management progression beyond 2 mg. The molecule is identical; the difference is target dose and indication.

The reconstitution math is unaffected by which titration pattern is followed. DrawDose accepts any target dose and returns the unit draw at the chosen concentration.

Adverse reactions per FDA labeling

Per the Ozempic and Wegovy prescribing information, the most common adverse reactions reported in the SUSTAIN and STEP clinical trials were nausea, vomiting, diarrhea, abdominal pain, and constipation. Frequency was dose-dependent, with higher rates at the higher titration steps. Nausea was reported by approximately 16 to 44% of patients across studies, depending on dose and indication.

Both labels carry a boxed warning for thyroid C-cell tumors based on rodent carcinogenicity studies. Per the prescribing information, semaglutide caused thyroid C-cell tumors at clinically relevant exposures in rats; the human clinical relevance is described as undetermined. Both Ozempic and Wegovy are contraindicated in patients with personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

Other documented adverse reactions per the prescribing information include acute pancreatitis, acute kidney injury (often associated with severe dehydration from gastrointestinal effects), diabetic retinopathy complications in patients with type 2 diabetes, hypoglycemia (particularly when combined with insulin or sulfonylureas), and gallbladder disease. Suicidal ideation and behavior were investigated by the European Medicines Agency and the FDA in 2023 to 2024; per FDA's published review, no causal association was established.

Community survey data layers temporal patterns on top of the label's frequency data. Nausea is most commonly reported within 24 to 72 hours of each dose increase, with adaptation typically occurring within two weeks at any given step. Sulfur burps (eructation with characteristic sulfur taste) are documented in user reports as a manifestation of delayed gastric emptying, which is one of the mechanisms by which semaglutide produces satiety. Severe gastroparesis cases have been reported in post-marketing surveillance and are described in the prescribing information warnings.

Common reconstitution errors

Compounded peptide forums and pharmacy QA literature document a recurring set of errors specific to compounded semaglutide.

Confusing milligram and microgram dosing. Semaglutide is dosed in fractions of a milligram (0.25 mg, 0.5 mg, 1.0 mg, 2.4 mg). Some users default to thinking in micrograms because other peptides are dosed in mcg; this leads to 1000-fold dosing errors. The Ozempic and Wegovy labels use mg consistently. Verify the unit before calculating any draw.

Switching between Ozempic-target and Wegovy-target without recalculating. The two protocols share early titration but diverge at maintenance. Using a 2.4 mg target with 1 mg/mL reconstitution requires a 240-unit draw, which exceeds the 1 mL insulin syringe capacity. The math has to be re-run for higher target doses, often with a more concentrated reconstitution.

Reusing reconstituted vials beyond 4 to 6 weeks. Per peptide stability literature, reconstituted semaglutide remains stable for approximately 4 to 6 weeks at 2 to 8°C with bacteriostatic water containing benzyl alcohol preservative. After that, peptide degradation accelerates and concentration drift becomes meaningful.

Trusting the vial label over the COA. Compounded vials run 5 to 15% off label in industry-published variance data. The COA reports the actual measured peptide content per the lot's HPLC and mass spec assays.

Storing reconstituted vials in the refrigerator door. Door storage cycles through temperature variation each time the door opens. The back of the main compartment is the documented recommendation in peptide stability literature.

Storage and shelf life

Per peptide stability literature, reconstituted semaglutide stays stable for 4 to 6 weeks at 2 to 8°C (36 to 46°F) when reconstituted with bacteriostatic water. The benzyl alcohol preservative is what enables this; sterile water without preservative produces a 24-hour shelf life from first puncture.

Lyophilized semaglutide stores for 24 months or longer at -20°C and 12 months or longer at 2 to 8°C, per the same stability literature. Heat exposure during shipping is the most documented threat to potency. Branded Ozempic and Wegovy pens are stored unopened at 2 to 8°C and can be kept at room temperature for up to 28 days after first use per the manufacturer's prescribing information.

What to verify on a Certificate of Analysis

The COA reports the actual peptide content of a specific lot. Net peptide weight is the measured milligrams of peptide in the vial, separate from any excipients (mannitol, sodium chloride, phosphate buffer) included for stability. Purity by HPLC reflects the percentage of UV-absorbing material that is the target peptide; 95% is the research-grade minimum the peptide industry has converged on, and 98% is the standard most reputable vendors publish for semaglutide. Below 95%, a meaningful fraction of fragments and degradation products is present, with potential for reduced potency and unpredictable side effect profiles.

Mass spec confirmation matches the expected molecular weight (4,113.58 Da for semaglutide) and verifies the molecule is semaglutide rather than a similar GLP-1 analog mislabeled. The C18 fatty acid modification is detectable by mass difference and is the primary check against substitution with unmodified GLP-1.

Documented combinations

Combination protocols are reported in compounded-pharmacy literature and community surveys; none have published FDA-aligned trial data as combinations.

Semaglutide plus cagrilintide is documented in clinical research as the CagriSema investigational combination. Per Novo Nordisk's published Phase 2 trial data, the combination produces additive weight loss compared to semaglutide alone. CagriSema is in Phase 3 trials; it is not yet FDA-approved as a combination product. Some compounding pharmacies offer the combination off-label.

Semaglutide combined with tirzepatide is not documented as a stable practice. Both compounds are GLP-1 receptor agonists (tirzepatide adds GIP receptor activation); the GLP-1 receptor saturates with either compound alone, and co-administration produces the side effect load of two compounds with the efficacy of one. Sequential use (transitioning from semaglutide to tirzepatide or vice versa) is documented in clinical-practice guidelines.

BPC-157 is occasionally added in community protocols specifically for managing semaglutide-related gastrointestinal effects, with the rationale that BPC-157's gastric mucosa effects may offset semaglutide's delayed gastric emptying side effects. The combination is community-reported with no peer-reviewed support.

FAQ

How long does semaglutide take to start working?

Per the SUSTAIN and STEP trial data referenced in the prescribing information, appetite suppression typically appears within 48 to 72 hours of the first dose. Meaningful weight reduction begins around week 4 to 6, after the first titration up to 0.5 mg. Steady-state pharmacokinetics are reached after 4 to 5 weeks of consistent weekly dosing.

What's the difference between Ozempic, Wegovy, and Rybelsus?

All three are semaglutide. Ozempic is the subcutaneous formulation FDA-approved for type 2 diabetes (max 2 mg weekly). Wegovy is the subcutaneous formulation FDA-approved for chronic weight management (max 2.4 mg weekly). Rybelsus is the oral tablet formulation FDA-approved for type 2 diabetes, with an absorption enhancer for oral bioavailability. Compounded semaglutide refers to the same molecule prepared by compounding pharmacies in multi-dose vials, and is not itself FDA-approved.

Can a weekly dose be split into two injections?

The Ozempic and Wegovy labels specify once-weekly dosing. Some users in community protocol surveys report twice-weekly dosing at half the weekly amount to flatten side effect peaks. The total weekly milligrams is the same; the practice is off-label and not validated by clinical trial data.

What does the label say about a missed dose?

Per the prescribing information, if a missed dose is remembered within 5 days, take it as soon as possible. If more than 5 days have passed, skip the missed dose and resume the regular weekly schedule. Doubling up is not recommended. The half-life of approximately 7 days means a single late dose has limited effect on steady-state levels.

Is microdosing semaglutide safe?

There is no published clinical trial data on subcutaneous semaglutide doses below 0.25 mg. Some compounded pharmacies offer sub-0.25 mg formulations, and prescribers use them off-label for users sensitive to gastrointestinal effects. The safety and efficacy profile at sub-label doses is unknown rather than known-safe.

Should I expect to plateau on semaglutide?

Per the STEP trial data referenced in the Wegovy prescribing information, average weight loss in trial subjects continued through 68 weeks of treatment, with the rate of loss decreasing over time. Community survey data describes a typical pattern of meaningful weight loss through the first 6 to 9 months followed by a slower phase or plateau. Plateauing is documented; complete cessation of effect at maintenance dose is not described in clinical trial data.

Is semaglutide banned by WADA?

GLP-1 receptor agonists, including semaglutide, are not currently on the World Anti-Doping Agency Prohibited List. WADA reviews the prohibited substance list annually; verify the current list before assuming status for any peptide.