The Peer Review Bottleneck: Why Medical Journals Are Struggling to Find Reviewers in 2026

Medical authors already know that peer review is slow. What fewer appreciate is how much slower it has become, and why. Between 2018 and 2025, the rate at which academics accept peer review invitations fell by nearly half. Where journals once needed an average of 2.3 invitations to secure a single reviewer, they now need 4.5. The median time from manuscript submission to acceptance grew by 23 days over the same period. These are not temporary disruptions. They reflect a structural mismatch between a system built for the academic publishing volumes of a previous era and the submission loads it now faces.

The downstream effects touch every author submitting to a peer-reviewed medical journal. Longer first-response times. More rounds of revision because journals are reluctant to send a revised manuscript to a new reviewer pool. Editors tightening desk rejection criteria to protect already-stretched reviewer capacity. And a growing gap between high-volume publishers, which have begun automating parts of the intake process, and smaller specialty journals, which are often running on volunteer labor and facing the same capacity constraints with far fewer resources.

Understanding why the reviewer pool is contracting, how journals are responding, and what authors can do to adapt will not make peer review faster on its own. But it changes how you prepare a submission, which journals you choose, and how you manage a manuscript that has been sitting in review for longer than expected.

The Numbers Behind the Shortage

The clearest way to describe the problem is through invitation economics. A journal editor does not send one invitation and wait. They typically send out a batch, accounting for the fact that most invitees will decline. In 2018, reaching one willing reviewer required roughly 2.3 invitations. By 2025, that number had grown to 4.5. For a journal that needs two external reviewers per manuscript, that means sending an average of nine invitations just to staff a single decision. At high-volume journals receiving hundreds of new submissions each month, this is a significant operational load.

The 23-day increase in median submission-to-acceptance time reflects this cascading delay. Some of that extra time is absorbed at the reviewer recruitment stage. Some appears later, when reviewers who accepted take longer to respond because they are managing larger workloads. And some reflects a quiet shift in how journals handle revision: editors are less inclined to send a fully revised manuscript back to the original reviewer pool and more likely to make internal decisions, which occasionally requires recruiting entirely new reviewers familiar with the revision.

These numbers vary significantly by field and by journal tier. High-impact general medical journals such as NEJM, The Lancet, JAMA, and BMJ operate at desk rejection rates that can exceed 80 to 90 percent, which means their external review load is smaller relative to submissions than the numbers suggest. But the manuscripts they do send out are often highly complex, require specialist reviewers with narrow expertise, and involve complex multi-round negotiations. The reviewer scarcity problem shows up there as difficulty finding the right expert, not just any willing body. At specialty journals, the problem is more fundamental: the pool of researchers qualified to review a given manuscript may genuinely be small, and the people in that pool are receiving more invitations than they can accept.

Why Researchers Are Saying No More Often

Peer review has always been unpaid. What has changed is the volume of invitations, the average complexity of manuscripts landing in inboxes, and the wider acknowledgment that reviewing consumes significant time with essentially no formal career return in most academic environments. A researcher who publishes regularly in a field will receive substantially more review requests than they generate, because journals invite a wide pool to compensate for expected declines. That math has worsened as submission rates rose post-pandemic.

Academic medical researchers face a specific version of this pressure. Clinical research manuscripts are often lengthy, data-heavy, and require engagement with both the statistical methods and the clinical context. A thorough review of a randomized controlled trial or a large registry study can take four to eight hours. For a clinician-researcher juggling patient care, grant applications, and teaching duties, that is a meaningful commitment. The psychological distance between receiving a review invitation and completing a review has grown, even for researchers who value the process.

There is also a generational element that editors discuss openly. Established researchers who built their careers partly through consistent reviewing are gradually withdrawing from the pool as they retire or reduce their publishing activity. Junior researchers, who might form the natural replacement pool, face a different incentive structure: they are often not yet deeply integrated into the invitation networks that journals maintain, and they are disproportionately cautious about committing to reviews outside their narrow specialization. The middle tier of mid-career researchers, who are both qualified and still active, is stretched particularly thin.

The growth of AI-assisted writing tools has added another layer. When draft manuscripts become easier to produce, publication output rises, and it has. More manuscripts submitted does not mean more qualified reviewers available. If anything, concerns about the quality of AI-assisted manuscripts have made the review task more demanding, not less, because reviewers now carry an informal expectation of scrutinizing reference accuracy, methodological coherence, and logical consistency more carefully than they might have a decade ago.

How the Bottleneck Shows Up in Practice

Authors usually experience the reviewer shortage as unexplained waiting. The submission system shows a status like "Under Review" or "With Editor" for weeks without movement. What that status often conceals is an editor still cycling through the invitation list, waiting for confirmations. The delay is invisible in the manuscript portal, but it is real and has grown substantially.

One consequence that authors sometimes misread as a quality signal is the rise in desk rejection rates at mid-tier journals. At PLOS ONE, for example, desk rejection rates reportedly climbed from roughly 13 percent to 40 percent after the publisher implemented pre-submission screening protocols. Some of that rise reflects genuine quality filtering. But a significant part reflects journals protecting their reviewer pools from submissions that cannot plausibly succeed at external review. The logic is that sending a weak or out-of-scope manuscript to reviewers burns goodwill. Journals that have learned this are pre-screening more aggressively, which means authors now face rejection before review at journals that previously would have sent those same manuscripts out.

For manuscripts that do reach external review, there is a subtler pressure. Editors are now making more use of single-reviewer decisions in cases where they might previously have required two. They are also extending the time window before sending reminder messages to reviewers who have not responded, partly to avoid pestering people who are already overextended. The result is that the middle section of the review process, from reviewer acceptance to first decision, has stretched even where the total number of rounds has not increased.

How Journals Are Responding

Publishers and editors are experimenting with several approaches, with varying degrees of effectiveness. The most visible change at large publishers is the introduction of pre-submission screening tools that filter out obviously unsuitable manuscripts before they enter the review queue. When those tools work well, they reduce the number of manuscripts editors need to send to reviewers, which partially offsets the shrinking acceptance rate on the reviewer side. But screening tools are imperfect, and the cost of false positives, desk-rejecting manuscripts that might have succeeded, is real and largely invisible from the editor's perspective.

Some journals are experimenting with reviewer payment. The models vary: one-time honoraria ranging from $50 to $300 per completed review, gift card incentives, or credits toward APCs at the same publisher. The evidence that payment substantially increases reviewer availability is mixed. The researchers who decline most invitations are often not declining for lack of compensation. They are declining because they are overloaded. But payment does seem to improve completion rates among reviewers who accepted an invitation, which reduces the problem of half-reviews that disappear.

Transparent peer review, now required at all papers accepted by Nature, has an indirect effect on reviewer scarcity. When review reports are published alongside papers, they become part of the academic record and can be cited. This creates a concrete career benefit for reviewers that anonymous reviewing does not offer. Whether it will meaningfully expand the pool of willing reviewers is still uncertain, but it changes the conversation about recognition in a way that purely nominal programs like Publons certificates do not.

A smaller number of journals are testing AI-assisted review preparation tools that help reviewers structure their reports, flag statistical concerns, or check reference accuracy. These tools are designed not to replace reviewer judgment but to reduce the mechanical labor involved in producing a thorough report. The ICLR and ICML conferences in computer science have both experimented with reviewer-assistance tools, with mixed results for quality and significant controversy over where the reviewer role ends and the tool begins. Medical journals are watching those experiments carefully before adopting similar systems.

What This Means for the Author Submitting Today

The most immediate practical implication is that reviewer suggestion quality matters more than it used to. Almost every major medical journal now offers authors the option to suggest preferred and non-preferred reviewers. When editors are struggling to staff a review, they lean more heavily on the preferred list than they did when the invitation acceptance rate was twice as high. This is not a formality. A submission that includes two or three specific, well-qualified preferred reviewers with no obvious conflicts gives the editor a workable shortlist. A submission that suggests vague categories ("any expert in cardiovascular imaging") does not.

The non-preferred list matters too, but for different reasons. Editors will try to avoid the researchers you exclude, but they will not abandon a strong candidate simply because they appear on your list without a clear conflict. If you include someone as non-preferred for reasons that look competitive rather than ethical, it adds friction without protecting you. Be specific and accurate in both lists, and only exclude people when there is a genuine reason.

Journal selection is now partly a reviewer-pool calculation, even if most authors do not frame it that way. A narrow subspecialty journal in a small field may have a severely constrained reviewer pool. A broader clinical journal may have better coverage. If you are submitting work in an area where the recognized experts number fewer than thirty worldwide and many of them are co-authors on your paper or direct competitors, you are asking the editor to solve a hard problem. A journal with a slightly broader scope may be able to review your paper faster and with less strain than the most targeted venue.

Waiting is also a more active choice now than it used to be. If your submission has been under review for significantly longer than a journal's stated turnaround time without correspondence, a polite inquiry to the editorial office is reasonable. Most journals now provide average first-decision times on their websites, or in recent published data. An inquiry framed around that stated average, "our submission has been under review for eight weeks and the website indicates average first decision at six weeks, could you give us an update," is appropriate and usually welcomed. The shortage means editorial offices are sometimes genuinely unaware that a reviewer fell out of the process without notice.

The Integrity Layer Making the Problem Harder

A complicating factor that does not get enough attention in discussions about reviewer scarcity is the growth of coordinated peer review fraud. Review mills, where individuals or networks submit generic reviews, often containing self-citations, in exchange for payment, have been documented in medical publishing for years, but the scale and sophistication of these operations has grown. An analysis published via medRxiv in late 2025 traced a sophisticated review mill operating specifically in gynecological oncology, showing how a coordinated network could game invitation workflows at multiple journals simultaneously.

PLOS became the first major publisher to deploy an AI tool specifically designed to detect duplicate or suspiciously similar peer review reports. By early May 2026, the publisher had flagged 55 articles for editorial notes or expressions of concern as a direct result of that screening. Wiley has deployed paper mill detection tools that reportedly flag as many as one in seven submissions across some of its portfolios. These integrity screening operations consume significant editorial resources, which would otherwise go toward managing the reviewer invitation process. They are not replacing the reviewer shortage problem but they are adding to the operational complexity that makes the problem harder to address.

For honest authors, the integrity screening layer means something practical: more of your submission will be evaluated by automated tools before it reaches a human reviewer, and the quality of your metadata, references, figures, and methods section matters at the intake stage in a way it did not a decade ago. A manuscript with inconsistent reference formatting, unusual authorship patterns, or figure files that trigger image integrity checks may spend time in administrative review before reaching the editorial queue, adding days or weeks to a process that is already slower than it used to be.

How to Choose Journals With Realistic Turnaround Times

Many journals now publish median or average time-to-first-decision statistics on their author information pages, or as part of their scope descriptions. These numbers should be treated as benchmarks rather than promises, because they reflect historical performance under different reviewer pool conditions than those of 2026. But they are still useful for comparison. A journal reporting a median first decision at three weeks is signaling a different operational posture than one where the stated average is twelve weeks.

It is also worth looking at the journal's peer review model directly. Open peer review journals like those in the Nature Portfolio that now publish full review correspondence have different reviewer incentives than journals offering anonymous review. PLOS journals offer signed and published reviews as an option. The BMJ and similar journals have long offered open peer review. Whether those models attract more reviewers or just different reviewers is genuinely uncertain, but they create a different risk-benefit calculation for the reviewer that may marginally expand who is willing to participate.

Registered Reports, which conduct peer review before results are collected, are one structural response to the reviewer supply problem that deserves more attention from medical authors. Because the review evaluates the design and rationale rather than the full results section, the cognitive load on the reviewer is more tractable. The manuscripts tend to be shorter. And the review process is often faster because the scope is bounded. Nature expanded Registered Reports to all disciplines in 2026, and while fewer than one percent of MEDLINE-indexed journals currently offer the format, that number is growing.

The Reviewer Role Authors Tend to Underestimate

Medical authors who are frustrated by slow peer review are frequently also declining review invitations from other journals. This is not a criticism: researchers have finite time and genuinely cannot accept every invitation they receive. But the math is worth sitting with. If every published researcher committed to reviewing approximately three papers for every one they submit, which is a rough traditional expectation, the system would be in balance. The gap between current submission rates and current reviewer acceptance rates suggests that balance has been lost, and the burden is falling on a shrinking core of active reviewers who accept far more than their proportional share.

For authors who have the capacity, accepting review invitations in areas where they have genuine expertise is one of the few direct ways to reduce the problem. Declining invitations for manuscripts outside your area is the right call, but reflexively declining everything creates the system that then delays your own papers. There is no formal mechanism enforcing this balance, which is part of why the system has drifted. But the relationship between reviewing and being reviewed well is real, even if it operates at the systemic level rather than the individual transaction level.

Where Peer Review Is Heading

The peer review system will not look the same in five years as it does today. The specific shape of what replaces or supplements the current model is still genuinely contested, but a few directions are becoming clearer. Payment for reviewing is gaining support and is no longer treated as a fringe proposal. The COPE and ICMJE have not yet formally endorsed reviewer compensation, but several publishers have moved ahead independently, and the conversation is becoming more mainstream in editorial circles.

AI-assisted review, where tools help reviewers work through a checklist, catch obvious errors, and structure their reports, is coming regardless of how medical journals feel about it. The ICMJE's January 2026 updates addressed AI use by authors and editors but were deliberately quiet on reviewer use, which reflects how unresolved the field remains. Expect clearer guidance in the next annual update. When it arrives, it will likely draw the same distinction that has emerged for author use: AI tools can assist, but the reviewer must verify, own, and sign what goes to the editor.

For authors right now, the practical conclusion is that peer review timelines should be treated as uncertain and longer than historical averages suggest. Build that into your publication planning, especially when submitting work tied to funding cycle reporting, graduation timelines, or grant renewal applications. A manuscript submitted in spring should not be expected to generate an accepted paper by summer in most medical journals. Adjust your backup plans and your parallel submission strategy accordingly, and choose journals where the gap between your submission and the likely first decision is something you can absorb.

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