AMA Citation Style: A Complete Guide

What is AMA citation style?

AMA style is defined by the AMA Manual of Style: A Guide for Authors and Editors (11th edition), published by Oxford University Press on behalf of the American Medical Association. It is required by major medical journals including JAMA, JAMA Internal Medicine, and JAMA Pediatrics, and is widely used in health sciences coursework, clinical research papers, and systematic reviews.

Like ACS style, AMA uses a numbered citation system: each source receives a number when it is first cited, and that number is reused every time the same source appears again. The matching reference list is ordered numerically — not alphabetically — so the reader can quickly locate the full entry behind any superscript in the text.

AMA style differs from ACS in several important ways: article titles are included in journal references, journal names follow specific medical abbreviations (not CASSI), author names use initials without periods, and up to six authors are listed before truncating with "et al."

In-text citations

AMA in-text citations are superscript Arabic numerals placed directly in the running text. They appear after punctuation such as commas and periods, but before a colon or semicolon. No parentheses are used around the number.

Numbers are assigned sequentially in the order sources first appear. Once a source has a number, that same number is used every time the source is cited again. If multiple sources are cited together, list their numbers in ascending order separated by commas, or use an en dash for a consecutive range.

Position relative to punctuation

AMA superscripts are placed after a period or comma but before a colon or semicolon. This is a common point of confusion for writers who are familiar with APA or MLA, which place parenthetical citations before the closing period.

Reference list rules

The reference list appears at the end of the document under the heading References. Each entry is numbered to match its superscript in the text and listed in citation order — not alphabetically.

Author names

Author names follow the format: Last Name Initials — no periods after initials, no comma between the last name and initials. Multiple authors are separated by commas. If a work has six or fewer authors, list all of them. If there are seven or more, list the first three and add "et al."

Journal name abbreviations

Journal titles are abbreviated in AMA references following the List of Journals Indexed in Index Medicus (now part of MEDLINE/PubMed). Abbreviated titles are not italicized in AMA style — this differs from ACS, where abbreviated journal names are italicized.

• New England Journal of Medicine becomes N Engl J Med
• JAMA: The Journal of the American Medical Association becomes JAMA
• The Lancet becomes Lancet
• British Medical Journal becomes BMJ

DOIs

When a DOI is available, include it at the end of the reference in the format doi:10.xxxx/yyyyy (note: AMA uses doi: as a prefix, not the full https://doi.org/ URL, though either is acceptable in practice). The DOI appears after the page numbers with no additional punctuation before it.

Journal articles

Journal articles are the most frequently cited source type in medical writing. The AMA format is:

Note that the journal name is abbreviated and italicized (unlike the reference number, which is plain text). The year is followed immediately by a semicolon — there is no space before it. Volume and issue are written as Volume(Issue) with no spaces, followed by a colon and the page range.

Online-only articles and article numbers

For articles published online ahead of print, include the year and add "Published online" with the date. For journals that use article numbers instead of page ranges, use the article number in place of pages.

Books and book chapters

Entire book

For a book, list the author(s) or editor(s), the title in italic, the edition if not the first, the publisher, and the year. No city of publication is required in the 11th edition of the AMA Manual of Style.

Chapter in an edited book

When citing a specific chapter, name the chapter author(s) first, then the chapter title, then introduce the book with "In:" followed by the editor(s), "ed." or "eds.", the book title in italic, publisher, year, and the page range of the chapter.

Websites and online sources

For web pages and online documents that are not formally published journals or books, AMA requires the author (or organization if no individual is named), the page or document title, the website name, the publication or update date, the access date, and the URL.

Government and institutional reports

Government agencies, health departments, and research institutions publish reports that are commonly cited in medical and public health writing. Treat these similarly to books, using the organization as the author when no individual author is named.

Common mistakes to avoid

Using periods after author initials

AMA style does not use periods after initials. "Smith J.A." is incorrect; the correct format is "Smith JA" — initials run together immediately after the last name with no punctuation between them.

Alphabetizing the reference list

Like ACS, AMA references are ordered by citation number — the order sources first appear in the text. Alphabetizing by author name is a common mistake made by writers accustomed to APA or MLA.

Listing all authors when there are seven or more

When a work has seven or more authors, only the first three are listed, followed by "et al." Listing all authors when the threshold is exceeded — or truncating too early (e.g., with only four or five authors) — are both errors.

Italicizing journal names incorrectly

Journal names in AMA references are abbreviated and italicized. Writing the full journal name, or forgetting the italics, are both formatting errors. Check PubMed's journal abbreviation list for the correct shortened form.

Wrong punctuation around year and volume

AMA format uses a specific punctuation pattern: year, semicolon, volume, issue in parentheses, colon, pages. A common mistake is placing a period or space where a semicolon belongs — for example, writing "2017. 377(12):1119" instead of "2017;377(12):1119."

Missing the access date for websites

Online sources always require an "Accessed Month DD, Year" statement. Omitting it leaves the citation incomplete, since readers cannot verify whether the version they retrieve matches the one you read.

Quick summary

AMA style is built for clarity and traceability in clinical writing. Its numbered system keeps the body text uncluttered while making every source easy to track down. Once you internalize the author format, the semicolon punctuation pattern, and the rule for truncating long author lists, producing correct AMA references becomes straightforward.