Talk:Beyond-use date

Request for comment. A survey of the dosing and handling articles finds the two terms used interchangeably in eleven places, and in four of those the interchange changes the meaning of the sentence. Questions for comment:

1. Should the wiki adopt a binding convention distinguishing the terms, or is this a matter for Project:Manual of style guidance only?
2. If a convention is adopted, what does it say about a manufacturer-specified period after first use — which is manufacturer dating, supported by stability data, applying to an opened container?
3. Should this article be the definitional home, with other articles summarising and pointing here? — — RfC_Rasmus (talk) 10:00, 2 February 2026 (UTC)

Binding convention, yes. The reason to make it binding rather than advisory is that the conflation is not a style preference: it produces false statements. "The vial expires 28 days after reconstitution" asserts a stability claim that nobody has made. Advisory guidance has been in place informally for a year and the eleven instances accumulated anyway. — — BUD_Bertram (talk) 12:31, 2 February 2026 (UTC)

Support a convention, and on question 2, the third category is real and needs its own term. In practice it is called an in-use period or in-use shelf life, and both are used in European labelling. It is manufacturer dating in every respect except that it applies after opening, so calling it a beyond-use date would be wrong in the same way the current conflation is wrong. — — Compounding_Cate (talk) 09:14, 3 February 2026 (UTC)

Support, with the observation that labels themselves are inconsistent — some carry "Discard after", some "Use within", some a date — so a convention will sometimes require us to characterise a label rather than quote it. That is acceptable provided we say which we are doing. — — LabelLibby (talk) 11:02, 4 February 2026 (UTC)

Support, and this article as the definitional home on question 3. It already carries the contrast table, which is the thing every other article needs to point at. Duplicating that table elsewhere is how the divergence started. — — NPOV_Nadia (talk) 10:48, 6 February 2026 (UTC)

Support all three. One drafting caution: a binding convention should govern the wiki's own prose and not force us to correct quoted material. Where a source says "expiry" of a compounded preparation, we quote it and note the term is being used loosely. — — Hedgerow_Hal (talk) 13:25, 9 February 2026 (UTC)

Closing. Consensus for a binding convention with three terms — expiration date, beyond-use date, in-use period — as set out by Cate; this article is the definitional home; quoted material is not to be silently altered, per Hal. The convention is now recorded at Project:Manual of style. The {{accuracy}} banner stays until the eleven instances are cleared. — — Ref_Desk_Ron (talk) 11:10, 24 February 2026 (UTC)

The worked example says a 28-day period from 12 March gives 9 April. Counting 12 March as day zero, 9 April is day 28; counting it as day one, 8 April is day 28. The article now says the convention differs between sources and that a date without a stated convention is ambiguous by a day, which is correct, but it then uses one convention without saying which. — — UnitAuditUwe (talk) 13:44, 2 October 2025 (UTC)

Fair. I have made the example state its own convention — count from the day of preparation, and the beyond-use date is the last usable day. The point of the paragraph is that the ambiguity exists, so demonstrating it while being ambiguous ourselves was not a good look. — — BUD_Bertram (talk) 16:11, 2 October 2025 (UTC)

One day out of 28 is under 4%, which sounds trivial until the period is 12 hours, where the equivalent ambiguity is the whole afternoon. Worth a clause noting the ambiguity matters more for short periods. — — PlainNumbersPip (talk) 09:26, 3 October 2025 (UTC)

Both changes in. The short-period point is a good one and I had not thought of it. ✓ Done — — UnitAuditUwe (talk) 08:39, 4 October 2025 (UTC)

§Opened containers ends with a paragraph on community practice for reconstituted vials. It is carefully hedged — borrowed values, no testing at either end — but it is still the only numerical guidance in the article that a reader outside a pharmacy could apply, and it will be read as a recommendation however it is worded. — — ScopeSeverin (talk) 10:52, 14 April 2026 (UTC)

The alternative is that a reader takes the compendial 28-day default and applies it to an unpreserved preparation, which is the actual error the paragraph exists to prevent. Describing the practice and saying it is untested is more protective than silence. — — HarmReductionHen (talk) 14:20, 14 April 2026 (UTC)

I would keep it but sharpen one clause: "untested at both ends" is doing a lot of work in a short phrase. Spelling out that neither the sterility of the preparation at 28 days nor the assay of the peptide at 28 days has been measured makes the gap concrete rather than gestural. — — EndotoxinEd (talk) 09:07, 15 April 2026 (UTC)

That would address most of my discomfort. I am not proposing removal, only registering that this is the paragraph most likely to be quoted out of context. — — ScopeSeverin (talk) 11:34, 17 April 2026 (UTC)

Ed's sharpening is now in. Leaving the thread open, since Severin's underlying point about out-of-context quotation has no fix at the article level. — — BUD_Bertram (talk) 09:48, 14 July 2026 (UTC)

We now have compendial default tables here and a stability table elsewhere, and a reader wanting to know how long something lasts will find two articles with different tables and no statement of how they relate. The relationship is that one is microbiological and conventional and the other is chemical and empirical, which is exactly the article's main theme — but neither table says so. — — CrossRefCleve (talk) 10:15, 20 July 2026 (UTC)

That is a genuine navigation problem rather than a content one. A sentence in each table's caption stating what kind of limit it represents would fix most of it. — — StabilityStig (talk) 08:33, 21 July 2026 (UTC)

Captions plus a reciprocal cross-reference. I can do the cross-reference; the captions want someone who knows which chapters each table came from. — — SeeAlsoSelma (talk) 09:41, 22 July 2026 (UTC)