How to Store Peptides and Log Vial Expiry
Storage conditions for a peptide come from its label or from whoever supplied it, not from a general rule, and they differ from one product to the next. What a tracker adds is the dates: when a vial arrived, when it was opened or mixed, and when it has to be discarded. Pepti keeps those dates on your iPhone and alerts you as an expiry approaches. It never tells you what dose to take.
By Tessaro Pty Ltd, the maker of Pepti · Reviewed
This page explains what an expiry date means, shows from real product labels how much storage rules vary, and sets out what to write down for every vial. It does not tell you how to store any particular product: for that, the label or the source of your own material is the authority. It is written by the maker of Pepti, so read the Pepti-specific parts as a description of our own app.
Get Pepti on the App StoreWhat an expiry date actually means
An expiry date is a statement about stability under stated conditions. The US Food and Drug Administration describes it as reflecting “the time period during which the product is known to remain stable, which means it retains its strength, quality, and purity when it is stored according to its labeled storage conditions” (FDA, Expiration Dates: Questions and Answers).
Two things follow for anyone keeping a record. First, the date and the storage conditions are a pair. The date holds only if the conditions were met, so a log needs both. Second, the printed date describes the unopened product. Once a pen is in use or a powder has been mixed, the label often sets a separate limit.
Storage rules differ from one product to the next
Approved products print their storage rules on the label, and reading a few side by side shows why no rule can be borrowed from one product for another.
| US label | Unopened | Once in use or mixed |
|---|---|---|
| Semaglutide injection (pen) | Stored in a refrigerator; not to be used if it has been frozen | “the pen can be stored for 56 days at controlled room temperature” or in a refrigerator |
| Tirzepatide injection (single-dose pen or vial) | Stored in a refrigerator, “in the original carton to protect from light” | May be kept unrefrigerated “for up to a total of 21 days” |
| Tesamorelin for injection | The unmixed vial is kept at room temperature | “If not used immediately, discard the reconstituted solution” |
| Elamipretide injection | Stored refrigerated | “Discard vials 8 days after first opening” |
Four products, four different answers. These limits belong to those approved products and their specific formulations. They cannot be transferred to a different product or to a compounded or research vial of the same compound.
Opening or mixing a vial starts a new clock
The labels for the two common diluents make the same point from the other side. Both Bacteriostatic Water for Injection and Sterile Water for Injection carry the same instruction: “Do not store reconstituted solutions of drugs for injection unless otherwise directed by the manufacturer of the solute”. How long a mixed vial may be kept is decided by the product being mixed, not by the water it was mixed with.
For a record, that means three dates per vial rather than one: the printed expiry, the date it was opened or mixed, and the discard-by date that follows from whatever instruction applies to it. Some labels ask for exactly this. The elamipretide label tells patients to write a “Discard After” date on the vial, and the instructions for the semaglutide prefilled syringe say: “Record the date your prefilled syringe was removed from the refrigerator”.
Compounded and research vials
A compounded vial does not carry an approved product label. The FDA states that “a compounded drug is not approved by FDA”, and that the agency does not verify the quality of compounded drugs before they are marketed (FDA, Compounding and the FDA). The storage instruction and the discard date on a compounded vial therefore come from the pharmacy that prepared it, and they apply to that preparation only.
For a research peptide with no approved product anywhere, such as BPC-157, the instruction is whatever the source of the material specifies. This page supplies no figure for either case. If a vial arrives with no storage instruction at all, record that fact instead of borrowing a figure from a different product.
What to log for every vial
- Date received — how long it has been in your keeping.
- Expiry or discard date, as printed — copied from the vial or carton, not estimated.
- Storage statement, word for word — the other half of the expiry date.
- Where it is kept — which fridge, which shelf, which drawer.
- Date opened or mixed — the start of the second clock.
- Discard-by date after opening or mixing — taken from the label or the source of your material. If you were given none, write that down.
- Lot or batch number — the link between this vial and everything logged from it. Our guide to reading a vial label explains where to find it.
- Excursions — any time the vial spent outside its stated conditions: left on a counter, a power cut, a journey. Note the date and roughly how long.
A storage log makes the awkward questions answerable
Most storage questions arrive after the fact: a fridge door left open overnight, a parcel that sat on a doorstep. Whether the product is still usable is a question for its label, the pharmacy that supplied it, or whoever directs your care. What they will ask is exactly what a log holds: which product, which lot, how long it was out, and what its label says. Without the log, every answer is a guess.
How Pepti keeps the dates
In Pepti each vial or pen is its own record. You enter the expiry date printed on it, where it is stored, the vendor and the lot or batch number, and what it cost. For a powder you mix yourself, the app records the date you marked it as reconstituted and the water volume you enter. Pepti then alerts you when its expiry or use-by date is approaching.
Pepti does not work out how much is left or project a run-out date. The dates it keeps are the expiry you enter and, for a mixed vial, the shelf life you enter counted from the mixing date, so the expiry is never a guess.
The reconstitution log guide covers what to write down when you mix, and the guide to choosing a peptide tracking app explains how the vial record fits with the injection log.
Storage away from home
Away from home the label’s storage statement still governs, including any period it allows outside a refrigerator. Our guide to travelling with peptides covers what to check before you leave and how to log the hours a vial or pen spends in transit.
Sources (8)
- US Food and Drug Administration — Expiration Dates: Questions and Answers. fda.gov
- US Food and Drug Administration — Compounding and the FDA: Questions and Answers. fda.gov
- Semaglutide injection — US FDA label, storage and handling. FDA label (DailyMed)
- Tirzepatide injection — US FDA label, storage and handling. FDA label (DailyMed)
- Tesamorelin for injection — US FDA label, dosage forms, storage and handling. FDA label (DailyMed)
- Elamipretide injection — US FDA label, storage and instructions for use. FDA label (DailyMed)
- Bacteriostatic Water for Injection, USP — US product label. FDA label (DailyMed)
- Sterile Water for Injection, USP — US product label. FDA label (DailyMed)
Common questions
What does the expiry date on a peptide vial mean?
The FDA describes a drug expiration date as the period during which the product is known to remain stable, keeping its strength, quality and purity, when it is stored according to its labeled storage conditions. The date and the storage conditions go together: the date holds only if the conditions were met. It also describes the unopened product, so a pen in use or a mixed vial may have a separate limit stated on its label.
How long does a peptide last after it is reconstituted?
It depends on the product, and the label or the source of your own material is the only authority. Approved labels differ widely. The US label for tesamorelin for injection says to discard the reconstituted solution if it is not used immediately, while the label for elamipretide injection says to discard vials 8 days after first opening. Diluent labels say not to store reconstituted solutions unless the manufacturer of the product directs otherwise. This page gives no figure for compounded or research material.
Do peptides need to be kept in the fridge?
Some do and some do not, which is why the label matters. The US labels for semaglutide injection and tirzepatide injection say to store them in a refrigerator, with a stated period allowed outside it. The US label for tesamorelin for injection says to keep the unmixed vials at room temperature. Follow the storage statement on your own product, and copy it into your log word for word.
What should I write down when I store a vial?
Record the date you received it, the expiry or discard date as printed, the storage statement word for word, where it is kept, the date you opened or mixed it, the discard-by date that applies after opening, and the lot or batch number. Note any time it spent outside its stated conditions.
Does Pepti tell me what dose to take?
No, nowhere, by design. You enter a figure you already have and Pepti records it with the date, time, injection site and vial. It never suggests, recommends, or calculates what that figure should be. That is a decision for you and whoever directs your care, and Pepti stays on the record-keeping side of that line.
Is my data private?
Pepti has no account and no sign-up, and your protocol and health data stay on the device. There is no cloud sync. That data leaves your phone only if you turn on the AI coach or lab-report import, both behind one consent switch, and then only your coach messages with the app context they need, or the report you import, are sent to Pepti's server and processed by Anthropic. With both off, none of it is held on a server for anyone to lose, sell, or hand over.
If you keep vials or pens at home and want their dates and lot numbers in one private record on your iPhone, Pepti is built for that. If you would rather keep a paper log, the fields above are the ones to copy.
Get Pepti on the App StoreThis page describes record-keeping. It does not tell you how to store any product, and it provides no dose figure and no schedule. Storage and discard instructions come from the product label or the source of your own material.
Not medical advice. Pepti is a record-keeping tool, not a medical device.
Pepti – Peptide Tracker · Guides · Reviewed October 2026 · Editorial policy · About