How Recent Do Sources Need to Be in a Literature Review? (2026)

That distinction is worth getting straight before you delete a single reference.

Currency in a literature review means two separate things. The first is the publication age of the studies you cite, which is a convention your institution and discipline set, and which varies a lot. The second is the date you last ran your searches, which is a reporting requirement with an actual number attached to it. Students worry almost entirely about the first. Examiners and journals increasingly ask about the second.

Do my sources have to be from the last five years?

No, not as a universal requirement, although several universities do set five years as the default for current empirical research. Walden University’s doctoral literature review guidance tells students that "much of your literature review will focus on the current research being done in your field, meaning research conducted within the last five years" (Walden University Library, Literature Review: Scope). Southern New Hampshire University’s library sets a different default again, advising students to "use sources published in the past 5 years for research in the arts, humanities, literature, history, etc." (SNHU Library, How old should or can a source be for my research?).

The University of Worcester in the UK declines to give a number at all. Its library guidance says "the age for a source to be considered ‘too old’ depends on the field of study and the type of research you are doing" (University of Worcester Library, How old is too old?).

So three universities, three different positions, and none of them a rule you could apply blind. Check your own module handbook or rubric first, because where a number exists in writing, that number beats any general advice including this page.

What do different universities and standards actually say about how old a source can be?

The guidance splits into two groups: institutions giving a default publication age for sources, and methodology standards giving a maximum age for your search. These are the positions stated on each primary guidance page, read in September 2026. Walden’s and Rasmussen’s pages now sit behind a student login, so those two rows link to the most recent public archived copy.

Read down that table and the pattern is clear. Every number attached to source age is departmental. Every number attached to search age is methodological.

Which subjects expect sources newer than five years?

Fast moving applied fields expect sources newer than five years, and some set the bar at two to three. Southern New Hampshire University’s library guidance is explicit that "for faster-paced fields, look for sources published in the past 2-3 years", and it names sciences, healthcare, nursing, engineering, business, finance and social sciences as the disciplines it has in mind.

Clinical fields give a reason rather than a convention. Rasmussen University’s nursing guidance justifies its five year limit on the grounds that "the use of sources older than 5 years may lead to clinical decisions that are not optimal for patients" (Rasmussen University Library, Why do my sources need to be published within the last 5 years?). That is a patient safety argument, not a formatting preference, which is why nursing and allied health supervisors tend to be strict about it where a history supervisor would not be.

Williams College Libraries puts the spread plainly: "science papers need up-to-the-minute information, while social studies projects can use works published years ago; humanities papers often rely on sources decades or centuries old" (Williams College Libraries, Evaluating Sources: Currency).

When is it fine to cite a paper from the 1980s?

It is fine when the paper is the foundational or seminal work your field still builds on, and every university guidance page reviewed for this article carves out that exception. Walden University states that "the foundational or seminal research in your field is almost always older than five years", and adds that foundational literature "may have been published in a book, and not in a peer-reviewed journal", which matters if your rubric also demands peer reviewed sources.

The University of Worcester makes the same allowance in wider terms, saying that "classic studies, key papers, or theories can be relevant regardless of age, and are often referred to in later works", and that "historical texts, original works of literature, and philosophy are useful in some subject areas, again, regardless of age."

The practical test is whether the old paper is doing work that a newer paper could do instead. Citing a 1980s paper for the theory it introduced is defensible. Citing a 1980s paper for a prevalence figure, when three studies since 2020 report that figure, is the thing your examiner will circle. If you are unsure which category an old paper falls into, appraise it properly rather than guessing from its date.

What currency rule is actually written into methodology standards?

The one hard number in this area applies to your search date, not to your sources. Cochrane’s conduct standard C37 requires that searches for all relevant databases "be run (or re-run) within 12 months before publication of the review or review update, and that the results are screened for potentially eligible studies" (Cochrane, Reporting search dates). Cochrane Hepato-Biliary states the working version of the same rule for authors: searches "must be rerun close to publication if the initial search date is more than 12 months (preferably six months) from the intended publication date" (Cochrane Hepato-Biliary, Searches for studies).

PRISMA 2020 then makes that date public. Checklist item 6 requires authors to "specify the date when each source was last searched or consulted" (Page et al., The PRISMA 2020 statement, BMJ 2021), which means a reader can calculate how stale your evidence base was on the day you submitted.

Those standards were written for systematic reviews, and a taught masters literature review is not held to them. They are still the clearest statement in the field of what "current" means, and a supervisor who says your review feels dated is usually reacting to a search that was run eighteen months ago and never repeated.

How do I check whether my literature review has gone out of date?

Rerun your exact search string, restricted to the period since you last searched, and count what comes back. If the rerun returns nothing relevant, your review is current and you now have a defensible date to report. If it returns papers you would have included, your review needs updating rather than defending, and the gap is usually in where you searched rather than in how hard you looked.

A useful benchmark for how stale is too stale comes from Cochrane’s conduct standard C37, which requires that searches for a systematic review be run or re-run within 12 months before publication. A taught masters literature review is not bound by that standard, and 12 months is still a reasonable self-imposed limit for a dissertation chapter.

Four checks are worth running together before you submit. Rerun the search with a date filter covering the months since your last search, using the same databases and the same string, so the comparison is honest. Read the titles rather than the abstracts on the first pass, because a rerun is a sweep and not a screening exercise. Check your key citations for retractions, because a retracted paper is a worse problem than an old one. Record the date you finished, so you can state it if you are asked.

Litrevu is an AI literature review assistant that turns the papers a researcher has already gathered into a cited first draft, with every citation traceable to the uploaded source. Because a draft is built only from the PDFs you uploaded, the publication years in the draft are the publication years of your own reading, which makes an ageing evidence base visible on the page rather than buried in a folder.

The shape of that output looks like this. The block below is a format illustration, not a real result, and the tokens stand in for whatever your own uploaded papers say:

Three studies report on this outcome. (Author, Year) and (Author, Year) both find an effect in the same direction, while (Author, Year) reports no significant difference and attributes this to a different measurement window.

Every (Author, Year) token in a real draft resolves to one of the PDFs you uploaded.

Written out that way, a paragraph where every year in the brackets sits in the same decade tells you something a reference list sorted alphabetically never will.

Which tools help you check that a literature review is current?

Different tools solve different parts of the currency problem, and no single one covers it. The table below compares what each tool is actually best at, with no pricing comparison, because tool pricing changes often enough that you should read it on the vendor’s own page.

Elicit genuinely beats Litrevu at the first job on that list. If your problem is that you have not found the recent papers yet, a screening tool is the right answer and Litrevu is not, because Litrevu works from papers you have already selected. Scite is likewise the better choice if your specific worry is that a paper you cite has been contradicted since.

What should I do if my supervisor says my sources are too old?

Ask for the number, in writing, before you change anything. Supervisors mean different things by "too old", and the guidance they are drawing on ranges from two years in fast moving applied fields to no limit at all for theory, so the correction you make depends entirely on which they meant.

Once you have the number, find the rule in your own handbook or rubric and quote it back, because a written departmental threshold settles the question faster than any argument about convention. Then rerun your search for the period since you last ran it, so you are arguing from evidence rather than from memory. The fix is usually not deletion. Separate your reference list into foundational work and current empirical work, and the real complaint normally becomes visible: not that old papers are present, but that recent ones are missing.

If the rerun genuinely turns up little, say so explicitly in your methodology, along with the date you last searched. A stated search date is what PRISMA 2020 item 6 asks of published reviews, and it turns a vague criticism into a checkable claim.

Frequently asked questions

Is the five year rule real?

It is a real convention at some institutions and not a universal rule. Walden University and Rasmussen University both use five years as a default for current research, Southern New Hampshire University applies five years to arts and humanities but two to three years to faster moving fields, and the University of Worcester gives no fixed number at all. Your own rubric or handbook overrides all of them.

Can I cite a paper from 1975 in a 2026 literature review?

Yes, if it is foundational work your field still builds on. Walden University’s guidance states that seminal research in a field "is almost always older than five years", and the University of Worcester says classic studies and theories "can be relevant regardless of age". Cite the old paper for the theory or method it introduced, not for a statistic that newer studies have since updated.

How recent does my search have to be, as opposed to my sources?

Cochrane’s conduct standard C37 requires searches to be run or re-run within 12 months before a review is published, and Cochrane Hepato-Biliary advises rerunning if the initial search is more than 12 months, preferably more than six, from the intended publication date. Those standards bind systematic reviews rather than taught masters work, but they are the clearest benchmark available for what counts as a current search.

Do I have to say when I last searched?

For a published systematic review, yes. PRISMA 2020 checklist item 6 requires authors to "specify the date when each source was last searched or consulted". For a dissertation chapter it is usually optional, and it is still worth stating, because it converts a subjective complaint about dated sources into a fact an examiner can check.

My field barely has any recent papers on my topic. What then?

Say so directly in the review rather than padding the reference list with loosely related recent work. State the date you last searched, describe the databases and the string you used, and name the gap. A review that documents a thin recent evidence base is doing its job, and the absence of recent studies is often itself the finding that justifies your research question.