Semaglutide Reconstitution Calculator
Semaglutide is a GLP-1 analogue with 94% sequence homology to human GLP-1. It binds and activates the GLP-1 receptor, which regulates appetite and caloric intake through receptors in brain regions governing appetite, increases glucose-dependent insulin secretion, and slows gastric emptying. Its half-life is about one week, which is why the injectable products are dosed once weekly. Unlike most peptides in this library it is an approved medicine, sold as a ready-to-use solution in a prefilled pen: that product contains no powder and never needs mixing. The calculator above is for the compounded and grey-market vials sold as a lyophilised powder, which are not the approved product and carry none of its labelling. The published schedules below are quoted from FDA labeling, not recommendations.
What the evidence says
The published trials that established Semaglutide dosing are reported below, each with the paper it comes from. The structured range table — every range with its experience level, frequency and linked citation — lives in the Dosavy compound library.
Semaglutide at a glance
- Category
- GLP-1
- Half-life
- 7 d
- Routes
- Subcutaneous, Oral
- Regulatory status
- Approved
- Also sold as
- Ozempic, Wegovy, Rybelsus, GLP-1 analogue
Mechanism
A GLP-1 analogue with 94% sequence homology to human GLP-1. It selectively binds and activates the GLP-1 receptor, the target of native GLP-1, which regulates appetite and caloric intake; GLP-1 receptors are present in brain regions governing appetite. It also increases glucose-dependent insulin secretion and slows gastric emptying.
Reconstitution
Supplied as a ready-to-use solution in a prefilled pen. Not a lyophilised powder — no reconstitution is required or appropriate.
Storage
Refrigerate at 2°C to 8°C before first use; do not freeze. After first use, pens may be stored per the product label at room temperature or refrigerated for a limited period. Oral tablets are stored at room temperature.
Frequency in practice
Once weekly by subcutaneous injection, or once daily orally, depending on the product.
Regulatory
FDA-approved. Ozempic (subcutaneous) and Rybelsus (oral) are approved for type 2 diabetes; Wegovy (subcutaneous) is approved for chronic weight management. Prescription-only in the US, EU and Switzerland.
What to know before anything else
BOXED WARNING: In rodents, semaglutide causes dose-dependent thyroid C-cell tumors at clinically relevant exposures. Human relevance is undetermined.
Contraindicated with a personal or family history of medullary thyroid carcinoma (MTC) or Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).
Contraindicated after a prior serious hypersensitivity reaction to semaglutide, including anaphylaxis and angioedema.
Compounded semaglutide from non-FDA-registered sources is not the same product as the approved label and its dosing cannot be assumed to transfer.
Titration schedules exist to limit gastrointestinal adverse reactions; escalating faster than the label directs increases them.
Semaglutide questions
Does semaglutide need to be reconstituted, and why is it dosed once weekly?
It does not. Semaglutide is supplied as a ready-to-use solution in a prefilled pen, so there is no lyophilised powder to mix and no bacteriostatic water involved — reconstitution is neither required nor appropriate for the approved products. The weekly interval comes from the molecule itself: its elimination half-life is approximately 168 hours, about seven days, which is exceptionally long for a peptide. The same property means plasma concentrations take roughly five weeks to settle after a dose change, so effects and adverse effects both resolve slowly rather than within hours.
What dosing schedules are published for semaglutide?
The FDA prescribing information for Ozempic (section 2.2) directs starting at 0.25 mg once weekly for 4 weeks, increasing to 0.5 mg once weekly, then to 1 mg once weekly after at least a further 4 weeks, with a maximum of 2 mg once weekly for type 2 diabetes. The Wegovy label describes a separate weight-management product titrated every 4 weeks to a recommended maintenance dosage of 2.4 mg once weekly. Those are two approved products with two indications, not one continuous scale.
Is there an established dose for semaglutide?
Yes, unusually for this library — semaglutide has approved labelling and randomised controlled trial evidence behind it. That is exactly why the numbers should come from a label and a prescriber rather than from a forum. The label also gives the titration schedule a reason: escalation steps exist to limit gastrointestinal adverse reactions, and moving faster than the label directs increases them. The starting dosages, 0.25 mg weekly by injection and 3 mg daily orally, are initiation doses for tolerability and are stated not to be effective for glycaemic control on their own.
Are the oral and injectable forms interchangeable?
No. The Rybelsus label states explicitly that oral and injectable semaglutide are not substitutable on a milligram-to-milligram basis, which the numbers make obvious: the oral maintenance dosages are 7 mg and 14 mg once daily, against 0.5 mg to 2 mg once weekly by injection. The oral tablet also carries administration conditions the injection does not — taken on an empty stomach in the morning with no more than 4 ounces of water, waiting at least 30 minutes before food, drink or other oral medication. The label further specifies that two 7 mg tablets must not be substituted for one 14 mg tablet.
What are the boxed warning and contraindications?
Semaglutide carries a boxed warning: in rodents it causes dose-dependent thyroid C-cell tumors at clinically relevant exposures, and the human relevance of that finding is undetermined. It is contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2, and in anyone who has had a prior serious hypersensitivity reaction to semaglutide, including anaphylaxis and angioedema.
Can semaglutide be combined with tirzepatide or another GLP-1?
No. The Wegovy label's Limitations of Use section states that coadministration with other semaglutide-containing products or with any other GLP-1 receptor agonist is not recommended, and the Zepbound (tirzepatide) label says the same about any GLP-1 receptor agonist. The shared GLP-1 agonism is duplicative and compounds the class's dose-limiting gastrointestinal effects. This matters most when switching products: the labels point to stopping one and letting it clear rather than overlapping doses during a transition.
How is semaglutide stored, and does compounded material follow the same label?
Approved product is refrigerated at 2°C to 8°C before first use and not frozen; after first use, pens may be kept at room temperature or refrigerated for a limited period per the product label, and oral tablets are stored at room temperature. Compounded semaglutide from non-FDA-registered sources is not the same product as the approved label. Its storage conditions, concentration and stability are not covered by that labelling, and its dosing cannot be assumed to transfer.
The rest of the math
- Reconstitution calculatorThe full version of the tool above, with syringe barrel sizes and IU conversion.
- Vial longevityHow many doses a vial holds and the date it runs out.
- Cost per doseVial price against doses drawn, so two vial sizes can be compared honestly.
- Half-life and decayFirst-order clearance, time to steady state, and what remains at a given hour.
- GLP-1 titration scheduleEscalation steps and week-by-week timing for GLP-1 receptor agonists.
Same class as Semaglutide
You worked out the draw. Now log this dose.
A calculator answers once and forgets. Dosavy keeps the concentration you mixed, the doses you actually took, and a reminder for the next one — with the same evidence labels you see on this page.