Prolonged, recurrent and periodic fever

Overview & Definition

A child with fever that "will not go away" or "keeps coming back" is one of the most common reasons a general paediatrician is asked for an opinion. The trap is to lump these children together and start investigating blindly. The discipline Samuel Long set out was to let the fever pattern do the triage before ordering a single test, because the pattern — not the height of the fever — points to the diagnosis. [1]

Three patterns matter. Prolonged fever is a single continuous febrile illness that has outlasted the expected course of a self-limited infection; in practical terms, fever for more than 7 to 14 days (and classically beyond two weeks) without a diagnosis after an appropriate initial workup is termed fever of unknown origin. Recurrent fever is two or more discrete febrile episodes separated by fever-free intervals, with each episode resolving spontaneously and the child well between attacks. Periodic fever is the special subset of recurrent fever in which attacks recur at predictable, stereotyped (clockwork) intervals. [1] [13]

Your job at first contact is therefore narrow and decisive: confirm the pattern with a careful history and diary, screen for the dangerous mimics, and only then decide how deeply to investigate. Most recurrent fever in young children is repeated common infection — a pattern, not a disease — and the art is recognising the minority who have something serious, inherited or autoinflammatory. [1] [10]

References14Show ledgerHide ledger

1. [1]Long SS. Distinguishing among prolonged, recurrent, and periodic fever syndromes: approach of a pediatric infectious diseases subspecialist. Pediatr Clin North Am, 2005.PMID 15925664
2. [2]Marshall GS, Edwards KM, Butler J, Lawton AR. Syndrome of periodic fever, pharyngitis, and aphthous stomatitis. J Pediatr, 1987.PMID 3794885
3. [3]Thomas KT, Feder HM Jr, Lawton AR, Edwards KM. Periodic fever syndrome in children. J Pediatr, 1999.PMID 10393598
4. [4]Hofer M, Pillet P, Cochard MM, Berg S, et al. International periodic fever, aphthous stomatitis, pharyngitis, cervical adenitis syndrome cohort: description of distinct phenotypes in 301 patients. Rheumatology (Oxford), 2014.PMID 24505122
5. [5]Gattorno M, Hofer M, Federici S, et al. Classification criteria for autoinflammatory recurrent fevers. Ann Rheum Dis, 2019.PMID 31018962
6. [6]Renko M, Salo E, Putto-Laurila A, Saxen H, et al. A randomized, controlled trial of tonsillectomy in periodic fever, aphthous stomatitis, pharyngitis, and adenitis syndrome. J Pediatr, 2007.PMID 17719940
7. [7]Garavello W, Romagnoli M, Gaini RM. Effectiveness of adenotonsillectomy in PFAPA syndrome: a randomized study. J Pediatr, 2009.PMID 19464029
8. [8]Lantto U, Tapiainen T, Pokka T, Koivunen P. Tonsillotomy for Periodic Fever Syndrome: A Randomized and Controlled Trial. Laryngoscope, 2024.PMID 37477273
9. [9]Licameli G, Lawton M, Kenna M, et al. Long-term surgical outcomes of adenotonsillectomy for PFAPA syndrome. Arch Otolaryngol Head Neck Surg, 2012.PMID 23069819
10. [10]Wang A, Manthiram K, Dedeoglu F. Periodic fever, aphthous stomatitis, pharyngitis, and adenitis (PFAPA) syndrome: A review. World J Otorhinolaryngol Head Neck Surg, 2021.PMID 34430824
11. [11]Livneh A, Langevitz P, Zemer D, Zaks N, et al. Criteria for the diagnosis of familial Mediterranean fever. Arthritis Rheum, 1997.PMID 9336425
12. [12]Steichen O, van der Hilst J, Simon A, Cuisset L. A clinical criterion to exclude the hyperimmunoglobulin D syndrome (mild mevalonate kinase deficiency) in patients with recurrent fever. J Rheumatol, 2009.PMID 19531764
13. [13]Hooft A, Leighton M. Management of prolonged pediatric fever in the emergency department. Pediatr Emerg Med Pract, 2026.PMID 41570317
14. [14]Dizi Işık A, Akkoc G, Yilmaz S, et al. Pediatric fever of unknown origin: Diagnostic spectrum revealed by a multidisciplinary retrospective study. Eur J Pediatr, 2025.PMID 41109899