Caffeine Use in Sport: A Systematic Review and Meta-analysis of Acute Side Effects and Implications for Athlete Health and Safety
Negaresh R, Al-Riyami SAA, Ghahfarrokhi MM, Del Coso J, Karimi Z, Yaghoobi M, Bagheri R
Sports medicine (Auckland, N.Z.) · 0 citations
Review labels
Neutral facts our review recorded about how this study was done. They describe method, never whether we like the result.
How it was studied
- Design
- Meta-analysis (indexed by PubMed)
- Studied in
- People
- Main outcome
- Health markers and function
Who paid for it
- Funding
- Funding not disclosed
Publication
- Published
- 2026-04-25 · Sports Med · vol. 56 · issue 9 · pp. 2209–2229
- Publisher
- Springer Science+Business Media
- Cited
- 0 citations · more than 25% of similar papers · 0.0× the field average
- References
- 110 works
- Access
- Paywalled
- Research areas
- Coffee research and impacts · Pharmacology and Obesity Treatment · Heavy Metals in Plants
- Keywords
- Caffeine, Placebo, Randomized controlled trial, Athletes, Meta-analysis, Odds ratio, Incidence (geometry), Side effect (computer science), Systematic review
- MeSH
- humans, headache, caffeine, central nervous system stimulants, sports, randomized controlled trials as topic, athletes
7 authors
From IR, OM, ES
- Raoof NegareshFarhangian University
- Shihab Aldin Ahmad Al-RiyamiSultan Qaboos University
- Majid Mardaniyan GhahfarrokhiArak University
- Juan Del CosoUniversidad Rey Juan Carlos
- Zohreh KarimiIslamic Azad University, Science and Research Branch
- Marziyeh YaghoobiFarhangian University
Abstract
Background
Given the widespread use of caffeine among athletes, this meta-analysis quantifies the incidence of acute side effects associated with caffeine supplementation. Despite its well-established performance benefits, evidence on caffeine's side effects remains fragmented, as these outcomes are often reported only as secondary findings.
Objective
To address this gap, we systematically reviewed and meta-analyzed evidence from randomized controlled trials on acute caffeine-related side effects in athletes.
Methods
Following PRISMA guidelines, we searched five databases (MEDLINE, Scopus, Web of Science, Embase, Google Scholar) up to July 2025. Eligible studies were randomized controlled trials in athletes aged ≥ 15 years examining acute caffeine ingestion versus placebo with reported side effects. Risk of bias was assessed using PEDro and Cochrane criteria. Data on frequency and magnitude of side effects were pooled using random-effects meta-analyses, with subgroup and dose-response analyses.
Results
A total of 48 studies (940 athletes; 63% male, 37% female) were included in the systematic review, of which 38 were eligible for meta-analysis. The mean caffeine dose was 4.9 ± 2.4 mg/kg (range 1.3-12 mg/kg), commonly ingested as capsules or beverages. Compared with placebo, athletes who ingested caffeine self-reported significantly higher odds of headache (Log OR = 0.74, p fourfold higher odds compared with placebo), insomnia (Log OR = 1.20, p < 0.001), increased urine output (Log OR = 1.04, p < 0.001), anxiety (Log OR = 1.29, p < 0.001), and nervousness (Log OR = 0.82, p < 0.001). Meta-regression of dose-response effects showed a significant association between caffeine dose and tachycardia (slope = 0.31, p < 0.001), headache (slope = 0.23, p < 0.001), abdominal discomfort (slope = 0.29, p < 0.001), vigor/activeness (slope = 0.18, p < 0.001), increased urine output (slope = 0.28, p < 0.001), and anxiety (slope = 0.37, p < 0.001).
Conclusions
Caffeine intake in athletes increases the likelihood of side effects in a dose-dependent manner, with tachycardia, insomnia, abdominal discomfort, and anxiety being the most consistent. Evidence suggests that, compared with high doses (> 6 mg/kg), low to moderate doses (≤ 6 mg/kg) of caffeine may reduce the risk of side effects.
Abstract via Europe PMC. Copyright remains with the authors or publisher.
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