For drug names and units in manuscripts, use the generic name and add a brand only where the product matters. Give laboratory values in both local units and the International System of Units (SI), with a space before each unit symbol. Avoid error-prone forms such as .5 mg, and define abbreviations separately in the abstract, text and tables.
Section 16 of our author guidelines covers this in one sentence: "Write in clear scholarly English, use SI units, define abbreviations at first use, and follow standard nomenclature (genes, species in italics, drugs by International Nonproprietary Name)." For the language clause, see writing clear scientific English; this guide covers the rest.
Name each drug by its International Nonproprietary Name first
An International Nonproprietary Name (INN) is the generic name that the World Health Organization (WHO) selects for a pharmaceutical substance. WHO's guidance on INNs lists scientific literature among their intended uses. National names, such as the British Approved Name (BAN) and the United States Adopted Name (USAN), are "with rare exceptions, identical to the INN".
The INN for adrenaline is epinephrine. When the UK made the INN the correct name for most medicines in 2003–04, replacing names such as amoxycillin with amoxicillin, it kept adrenaline and noradrenaline as exceptions. Where readers may know the other form, add it in parentheses at first mention. Not every substance has an INN; WHO says the majority of pharmaceutical substances used in medical practice have one. Without an INN, give the national generic or chemical name, and name each herbal ingredient by its Latin binomial, in italics.
The International Committee of Medical Journal Editors (ICMJE) asks authors, in its recommendations on preparing a manuscript, to identify drugs by "generic name(s), dose(s), and route(s) of administration". That section does not use the term INN or mention brand names. Section 16 of our author guidelines is more specific: drugs by INN.
A brand name is worth adding when the product itself could change the result, such as a particular formulation. For a drug intervention, the examples under CONSORT 2025 item 13 list the generic name and the manufacturer. Put the generic name first, with the brand and manufacturer in parentheses and no trademark symbol. The naming rule for a suspected drug reaction is set out in writing an adverse drug reaction case report.
Report laboratory values in both local and SI units
The ICMJE Recommendations ask authors to report laboratory information "in both local and International System of Units (SI)", and let editors request non-SI units too. Temperatures go in degrees Celsius, and blood pressure in millimetres of mercury (mmHg) unless the journal requires otherwise.
Section 16 of our author guidelines says "use SI units". The ICMJE Recommendations, which our guidelines say Directive's editorial policies follow, add local units for laboratory values, so giving both meets each text. Where a journal page states something more specific, our guidelines give it precedence, so check the target journal's unit style. Write each pair in one fixed order, as in "[value] mmol/L ([value] mg/dL)". Cite the source of any conversion factor.
Write numbers and unit symbols the way the SI Brochure sets out
The SI Brochure of the International Bureau of Weights and Measures (BIPM), now the 9th edition (2019), updated in 2026, sets the rules for writing SI values:
- A space separates number and unit, even for degrees Celsius: 37 °C, not 37°C. The only exceptions are the plane-angle symbols °, ′ and ″, as in a 30° tilt.
- The space stays in an adjective: a 2 cm lesion.
- The per cent sign takes a space too (45 %); if the target journal prints 45%, follow the journal.
- Numbers between −1 and +1 take a leading zero: 0.25, not .25.
- Long numbers may be grouped in threes by a space, as in 43 279.168 29, never by commas or dots. Grouping is optional; four-digit numbers are usually left whole.
- The decimal marker is the point or the comma, whichever is customary in the language. Keep one number format per table column.
- Unit symbols are not abbreviations: no full stop, no plural (5 kg, not 5 kgs).
- The litre is l or L, and the microgram is µg. "cc" is not permissible; write cm³ or mL.
Treat ISMP's error-prone list as a safety convention, not as SI
The Institute for Safe Medication Practices (ISMP) publishes a List of Error-Prone Abbreviations, Symbols, and Dose Designations, drawn from reported medication errors. Its scope is clinical communication, such as prescriptions, labels and order-entry screens, not typesetting, but a paper that clinicians act on can mislead in the same ways.
Where ISMP and SI agree, follow both: 0.5 mg, not .5 mg; 10 mg, not 10mg; no full stop after mg or mL. ISMP adds that a whole-number dose takes no trailing zero, because 1.0 mg can be read as 10 mg. The rule covers whole-number doses only; it does not ask you to drop the zero from a measured mean of 1.0 reported to one decimal place. ISMP also advises against abbreviating drug names: it lists the abbreviation for methotrexate (MTX) as mistaken for mitoxantrone.
ISMP and the SI Brochure disagree on three points. ISMP prefers mcg, because µg can be mistaken for mg, but mcg is not an SI symbol. ISMP replaces the abbreviations for international units (IU) and units (U) with the word "units", while the SI Brochure, noting that WHO defines International Units for biological activity, abbreviates them as IU. ISMP puts commas in dosing units of 1,000 and above, a United States convention by its own note; the SI Brochure never puts commas between digit groups. On each point, follow the target journal's style and use one form throughout.
Define each abbreviation separately in the abstract, text and tables
ICMJE asks for standard abbreviations only and advises avoiding them in the title. At first mention, give the full term with the abbreviation in parentheses, unless it is a standard unit of measurement. So mg needs no definition, but "myocardial infarction (MI)" comes before MI is used alone.
Treat the abstract, the main text and each table or figure as separate first mentions. ICMJE notes that abstracts are the only substantive part of an article indexed in many databases, and the only part many readers read. A definition given only in the Introduction never reaches those readers. In the abstract, abbreviate only what is essential and repeated, as how to write a strong abstract advises. Column headers carry units, and each table footnote and figure caption defines its own abbreviations, as set out in preparing figures and tables for publication.
Do not coin an abbreviation for a term used only once or twice, and keep a running list while drafting. After each revision, check that every first use still carries its definition; a deleted paragraph can take one with it.
Put gene symbols and species names in italics
Section 16 of our author guidelines asks for genes and species in italics. The Human Genome Organisation (HUGO) Gene Nomenclature Committee (HGNC) endorses italic gene symbols, with roman type for proteins: BRAF (the gene) and BRAF (the protein). HGNC notes that some journals' policies prevent this, so check the target journal. Species take italics too: Staphylococcus aureus.
Wrong versus right: drug names and units in manuscripts
The examples below are invented to illustrate the forms; their numbers are not real data and are not dosing recommendations.
| Instead of | Write | Rule and source |
|---|---|---|
| A brand name alone | Generic name, then brand and manufacturer in parentheses where the product matters | Generic name: ICMJE. INN: section 16 |
| adrenaline, for an international readership | epinephrine (adrenaline) | INN, national name at first mention |
| 5-fluorouracil; MTX | fluorouracil; methotrexate | ISMP: an embedded number can be read as a dose; no abbreviated drug names |
| glucose [value] mg/dL alone | glucose [value] mmol/L ([value] mg/dL) | ICMJE: local and SI units |
| 37°C; 10mg | 37 °C; 10 mg | SI Brochure; ISMP agrees on 10 mg |
| .5 mg | 0.5 mg | SI leading zero; ISMP agrees |
| 1.0 mg, for a dose | 1 mg | ISMP trailing zero |
| 5 mgs.; 2 cc | 5 mg; 2 mL | SI: no plural, no full stop, no cc |
| 12.500 (a dot between digit groups) | 12 500 or 12500 | SI: no dots or commas between groups |
| µg and mcg in one paper | One form: µg, unless the journal prints mcg | SI symbol versus ISMP clinical form |
| MI defined only in the Introduction | Defined again in the abstract and each table footnote | Abstracts are often read alone; tables explain nonstandard abbreviations in footnotes (both ICMJE) |
Run this check on drug names, units and abbreviations before you submit
- Search each drug name: the INN, one spelling throughout, a brand only where the product matters.
- Search for ® and ™, a digit run into a unit (10mg, 37°C, but not an angle such as 30°) and a bare decimal point (.5); fix each one.
- Give every laboratory value its SI unit and, where the local unit differs, the local unit beside it.
- Keep each variable's unit the same in the abstract, text, tables and figures.
- Take µg or mcg, and the digit-group separator, from the journal's style; then search for the other form.
- List every abbreviation: none in the title, and each one defined at first use in the abstract, in the text and in every footnote or caption that uses it.
- Italicise gene symbols and species names; keep proteins in roman type.
- Repeat the whole check after each revision.
At Directive Publications, section 16 is the only part of our author guidelines on drug names, units and abbreviations. The submission checklist in section 18 does not list these items, so run the check above yourself. For a randomised trial, matching the manuscript to its EQUATOR checklist, as the guidelines ask, also covers the drug details in CONSORT 2025 item 13 (intervention and comparator; item 5 in CONSORT 2010). Accepted articles are copy-edited and typeset, but only essential corrections are possible at proof, so fix these points before you submit. If you spot an error in this guide, please report the problem to us.