Per vs ever: where does per belong on a drug label?

Per belongs in the lines that tie an amount to its unit: a quantity per dosage unit, milligrams per milliliter, a rate per minute. Swap in "ever", a real and correctly spelled word, and spellcheck has nothing to flag, but the line no longer says what the number counts.

This page is general information, not legal or regulatory advice.

For short words across all the sections, see how to proofread a drug label for meaning, section by section. This page covers per on its own: what it means, where the rules call for it, and how to search for the swap.

What each word means

Merriam-Webster gives per the sense for each, and as an adverb defines it as for each, or apiece. Ever means always, or at any time. One word divides an amount by a unit; the other is about time, and it can't do that job.

Where per belongs on a label

• Drug Facts. 21 CFR 201.66 says the Active ingredient heading is followed by the established name of each active ingredient and the quantity of each active ingredient per dosage unit. The heading itself names the dosage unit stated in the directions for use. The FDA's consumer page, The Over-the-Counter Drug Facts Label, says this part states the amount for each dosage unit.
• Prescription labeling. 21 CFR 201.57 says Dosage and Administration must give specific direction on dilution and preparation, including the strength of the final dosage solution in milligrams of active ingredient per milliliter of reconstituted solution unless another measure fits better, and, where needed, the rate of administration in milligrams per minute.

Our view: in these lines per is the hinge between a number and its unit. Swap it, and the number no longer says what it counts.

Why the swap reads fluently

Our view: readers check the number and the unit and skim the short word between them. Both words are common, and both sit comfortably in an English sentence, so the line still looks finished.

The live case

We have a live case where a warning line printed "ever" where "per" belonged: FDA DailyMed warning said "ever" instead of "per". The line still read as English; the amount it was meant to set did not survive.

How to search a label for the swap

Practice advice:

• Search for the wrong twin, "ever". It has no natural home in a quantity, rate or limit line, so read each hit in its sentence.
• Then read each number on the label with its unit. Between them, look for per, each or a unit word that makes the amount clear.
• Check that the dosage unit named in the Drug Facts Active ingredient heading is the one the Directions use. For Directions, see wrong words in Drug Facts Directions.
• Read rate lines aloud with for each in place of per. If the sentence stops making sense, the word is wrong.
• For warning lines, see wrong words in Drug Facts Warnings.

This is our reading of public guidance, not legal or regulatory advice.

Sources

• Merriam-Webster: per
• Merriam-Webster: ever
• eCFR: 21 CFR 201.66
• eCFR: 21 CFR 201.57
• FDA: The Over-the-Counter Drug Facts Label

Last reviewed: October 18, 2026

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Would spellcheck catch ever instead of per?

No. Ever is a real, correctly spelled word, so a spelling tool has nothing to flag.

Where does per matter most on a label?

In quantity and rate lines. 21 CFR 201.66 calls for the quantity of each active ingredient per dosage unit in Drug Facts, and 21 CFR 201.57 uses per milliliter and per minute for prepared solutions and rates.

Has ever for per appeared on a real label?

Yes, in a warning line. The case is linked in the live case section above.

How do I check a label for this swap?

Practice advice: search for ever, read each hit in its sentence, then read each number with its unit and the word between them.