The note that matters most is the one nobody writes down

The short answer: a useful peptide log records where each vial came from, not just when you used it. That means the compound, the vendor, the lot or batch number, the COA for that exact batch, the dates it arrived, was opened and was mixed, how it was stored, what you noticed, and when you had bloodwork.

Most tracker apps are built around the calendar: what, when, which site. That part is easy. The part almost nobody records is the vial's paper trail, and it's the only part that helps when something goes wrong.

Here's what to write down, and why each line earns its place.

Last checked October 21, 2026. This is about record-keeping, not dosing. Nothing here is medical advice.

Where I get mine: the vendors I use, and how I vetted them.

Because when something goes wrong, nobody else has the details. Not the vendor, not your doctor, and not the researchers trying to work out what these products do.

Look at what happened when researchers studied what people report about unapproved retatrutide. They read 148,640 Reddit posts and comments from 38,936 users. The limitation they flag, in their own words: "Product identity, purity, dose, route, treatment duration, concomitant medications, and medical history cannot be verified" (JAMA Network Open, Oct 1, 2026).

That sentence describes most people's records too. A good log fixes about half of it. You can't verify purity from your kitchen, but you can know exactly which batch you used, what its COA said, when you mixed it and what you noticed.

Ten fields, in two groups: the vial's paper trail and your own notes.

Two habits make the table work. Take a photo of every vial label the day it arrives, so the lot number survives a smudged label. And save the COA file next to the entry, not as a link, because vendor pages change.

I use PeptIQ for this: peptiq.io. The parts that match this list are vial tracking (the App Store listing says it tracks "vials on hand, amount left, low stock and expiration") and bloodwork, which it describes as "Upload bloodwork and keep lab results in one timeline" (App Store listing). Each entry takes "date, time, site, and notes," and it exports to CSV or PDF (peptiq.io/features). Whatever you use, the fields above are the point, not the app.

Because a COA only means something for the batch it tested. A lot number is how you prove your vial came from that batch.

A COA, or certificate of analysis, is a lab report on one production run. If the lot on your vial doesn't match the lot on the COA, the report isn't about your vial. If you've never checked, here's how to read a peptide COA and what the numbers on it mean.

Lot numbers matter even in the regulated world. In December 2025, FDA warned about counterfeit Ozempic labeled "with lot number - PAR1229 - which also is an authentic lot number" (FDA, Dec 5, 2025). A lot number alone doesn't prove a product is real. But without one written down, you can't even check.

Two more reasons:

Because the clock that matters starts when you mix it, and for most research peptides nobody has published how long that clock runs.

There's no published stability data for BPC-157, TB-500, CJC-1295, ipamorelin, MOTS-c or retatrutide once they're mixed with bacteriostatic water. The "28 days" rule you've seen is a sterility rule for multi-dose vials, not proof the peptide is still intact. I went through what the labels and the little data that exists actually say in how long mixed peptides last in the fridge.

What a mix date gives you is a way to connect a change to the vial's age. If something felt different in week four of a vial and not week one, you'll only know if the date is written down. Same for storage slips. "Left out overnight" is a one-line note that could explain a lot later.

Because a side effect you didn't write down didn't happen, as far as anyone else will ever know. And reports on unregulated products are still thin.

JAMA put it plainly in October: "There have been scattered reports of adverse events associated with black market retatrutide." The same piece cites a Public Citizen count, based on FDA adverse event data, that "at least 14 users have been hospitalized," and six cases of liver toxicity reported to health officials in Victoria, Australia, linked to products labeled retatrutide (JAMA, Oct 9, 2026).

Two more data points from the same month:

None of that says your vial is dangerous. It says the record is thin, and the records that exist are hard to trace back to a product. A log with lot numbers is the fix.

Where to report. FDA's MedWatch program takes reports from "health professionals, patients and consumers," not just doctors (FDA MedWatch). A report with the compound, vendor, lot number and dates is far more useful than one without. If a reaction is serious, get care first. The log can wait.

How to write the note itself:

Because lab results without context are just numbers. With a date, you can see what you were using when the blood was drawn.

You don't need the full results in the log. You need the date, the lab, and where the report lives. Then, months later, you can line up a change on a panel with the vial, the lot and the week. My own first month on retatrutide is written up here if you want an example of lining things up by date.

Any of them works if you fill in the fields. The format is the least important decision here.

The test for any of them: can you answer "which lot was I using on this date, and what did its COA say?" in under a minute? If yes, your log works.

Want this without a spreadsheet? I log mine in PeptIQ. My vendors and tools are on this page.

Reply and tell me what you log that I didn't list here. If you've ever traced a bad reaction back to a specific batch, I especially want to hear how you did it.