What to track in a peptide log, and why

The point of a peptide log is to answer questions later that memory cannot. It is a medication log with one extra layer, the vial, and the test for whether a field is worth recording is simple: in six weeks, would you be able to reconstruct it? If yes, it is optional. If no, it is the whole reason for keeping a log.

What should you record in a peptide log?

Record four fields for every dose: the compound, the amount in the units your protocol uses, the date and time, and which vial it came from. Everything else in a peptide log is an addition to those four.

One optional fifth field is the injection site, if your healthcare professional has asked you to rotate sites. It takes a second to record, and it turns injection site rotation into something to follow rather than guess.

Why record which vial a dose came from?

A unit figure only becomes a dose through the concentration of the vial it was drawn from: 10 units is 250 mcg only if that vial was reconstituted to 2.5 mg/mL. Without the vial link, a log of unit figures becomes unreadable the moment a second vial is mixed differently.

The same arithmetic runs the other way when a dose is set in mcg and has to be drawn in units, which is the conversion the peptide dosage calculator does for any vial.

What goes in the vial record?

Record the vial strength in mg, the diluent volume added and the date of first entry, once per vial. Together they give the concentration behind every dose drawn from it, and the date starts the in-use window.

• Vial strength in mg, as printed on the label.
• Diluent volume added, measured rather than estimated.
• Date of first entry, which is what the in-use window is typically counted from. CDC guidance is to date a multi-dose vial when it is first punctured.
• Resulting concentration, or simply let it be derived: strength divided by volume.

These are the details that are genuinely irrecoverable. Nobody remembers on day nineteen whether it was 2 mL or 3 mL, and the difference changes every dose calculation by a third to a half, depending on which way the error runs.

Are mood, sleep and weight worth logging?

Yes, as long as the log is read as what happened alongside what, never what caused what. A personal log has no control group and a sample size of one, so its job is to surface a pattern worth raising with your healthcare professional.

Weight, sleep, mood, energy, appetite, side effects or injection-site reactions, and free-text notes all belong here. Weeks vary for a great many reasons at once, and a healthcare professional has the context to interpret a pattern that the log alone cannot.

Why does consistency matter more than completeness?

A log with four fields filled in reliably every time is more useful than one with twelve fields filled in when there is time. Gaps are not neutral: a subjective score recorded only on notable days produces a record that is systematically biased toward notable days, and any pattern read from it is an artefact of when it was filled in.

Which argues for choosing a small set of fields and holding to them, rather than an ambitious set that degrades.

What makes a peptide log worth showing to a clinician?

A log is useful at an appointment when it covers a defined period with no unexplained gaps, marks missed doses as missed, and can be exported rather than recalled. A dated record and "I think I have been fairly consistent" are not the same input.

1. It covers a defined period with no unexplained gaps.
2. Amounts are in the units the protocol uses, not converted ad hoc.
3. Missed doses are marked as missed rather than absent.
4. It can be exported or shown directly, rather than summarised from memory.

That last point is the one that changes the conversation. Recall is the weaker input: a 2024 systematic review of 65 studies of people on long-term medication found that self-reports ran higher than indirect measures of how regularly doses were taken.

Should you keep a peptide log on paper, in a spreadsheet or in an app?

Paper suits one peptide on a simple schedule, and a spreadsheet suits someone who wants to chart their own data. An app, whether a general medication tracker app or a peptide-specific one, suits the moment of entry and can do the vial arithmetic for you.

All three work; they fail differently. Paper is frictionless to write and impossible to analyse. A spreadsheet analyses well but is often not open at the moment a dose is drawn, so entries tend to drift retrospective. An app is designed for the moment of entry, at the cost of being a specific tool you have to have. There is a fuller breakdown in peptide tracking app vs spreadsheet and in peptide tracker vs notes app.