ICD-10-CM Alphabetic Index · FY 2026 342 Entries
Fever in the ICD-10-CM Index ICD-10-CM
The main term Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) carries 342 index entries pointing to 130 ICD-10-CM codes. The default entry is R50.9, the code the bare main term maps to; every indented line below refines the term by site, cause, or type. Verify any candidate code in the Tabular List before using it.
✓ Built from the official CMS FY 2026 index fileEffective Oct 1, 2025 – Sep 30, 2026
342
Index Entries
130
Codes Referenced
R50.9
Default Code
F
Letter
342 of 342 shown
ICD-10-CM
Index Entries Under Fever 342 entries · 130 codes
Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) R50.9
abortus A23.1
Aden (dengue) A90
African tick bite A77.8
African tick-borne A68.1
American
mountain (tick) A93.2
spotted A77.0
aphthous B08.8
arbovirus, arboviral A94
hemorrhagic A94
specified NEC A93.8
Argentinian hemorrhagic A96.0
Assam B55.0
Australian Q A78
Bangkok hemorrhagic A91
Barmah forest A92.8
Bartonella A44.0
bilious, hemoglobinuric B50.8
blackwater B50.8
blister B00.1
Bolivian hemorrhagic A96.1
Bonvale dam T73.3 Non-billable
boutonneuse A77.1
brain see Encephalitis
Brazilian purpuric A48.4
breakbone A90
Bullis A77.0
Bunyamwera A92.8
Burdwan B55.0
Bwamba A92.8
Cameroon see Malaria
Canton A75.9
catarrhal (acute) J00
chronic J31.0
cat-scratch A28.1
Central Asian hemorrhagic A98.0
cerebral see Encephalitis
cerebrospinal meningococcal A39.0
Chagres B50.9
Chandipura A92.8
Changuinola A93.1
Charcot's (biliary) (hepatic) (intermittent) see Calculus, bile duct
Chikungunya (viral) (hemorrhagic) A92.0
Chitral A93.1
Colombo see Fever, paratyphoid
Colorado tick (virus) A93.2
congestive (remittent) see Malaria
Congo virus A98.0
continued malarial B50.9
Corsican see Malaria
Crimean-Congo hemorrhagic A98.0
Cyprus see Brucellosis
dandy A90
deer fly see Tularemia
dengue (virus) A90
hemorrhagic A91
sandfly A93.1
desert B38.0
drug induced R50.2
due to
conditions classified elsewhere R50.81
heat T67.01 Non-billable
enteric A01.00
enteroviral exanthematous (Boston exanthem) A88.0
ephemeral (of unknown origin) R50.9
epidemic hemorrhagic A98.5
erysipelatous see Erysipelas
estivo-autumnal (malarial) B50.9
famine A75.0
five day A79.0
following delivery O86.4
Fort Bragg A27.89
gastroenteric A01.00
gastromalarial see Malaria
Gibraltar see Brucellosis
glandular see Mononucleosis, infectious
Guama (viral) A92.8
Haverhill A25.1
hay (allergic) J30.1
with asthma (bronchial) J45.909
with
exacerbation (acute) J45.901
status asthmaticus J45.902
due to
allergen other than pollen J30.89
pollen, any plant or tree J30.1
heat (effects) T67.01 Non-billable
hematuric, bilious B50.8
hemoglobinuric (malarial) (bilious) B50.8
hemorrhagic (arthropod-borne) NOS A94
with renal syndrome A98.5
specified NEC A96.8
Argentinian A96.0
Bangkok A91
Bolivian A96.1
Central Asian A98.0
Chikungunya A92.0
Crimean-Congo A98.0
dengue (virus) A91
epidemic A98.5
Junin (virus) A96.0
Korean A98.5
Kyasanur forest A98.2
Machupo (virus) A96.1
mite-borne A93.8
mosquito-borne A92.8
Omsk A98.1
Philippine A91
Russian A98.5
Singapore A91
Southeast Asia A91
Thailand A91
tick-borne NEC A93.8
viral A99
specified NEC A98.8
hepatic see Cholecystitis
herpetic see Herpes
icterohemorrhagic A27.0
Indiana A93.8
infective B99.9
specified NEC B99.8
intermittent (bilious) see also Malaria
of unknown origin R50.9
pernicious B50.9
iodide R50.2
Japanese river A75.3
jungle see also Malaria
yellow A95.0
Junin (virus) hemorrhagic A96.0
Katayama B65.2
kedani A75.3
Kenya (tick) A77.1
Kew Garden A79.1
Korean hemorrhagic A98.5
Lassa A96.2
Lone Star A77.0
Machupo (virus) hemorrhagic A96.1
malaria, malarial see Malaria
Malta A23.9
Marseilles A77.1
marsh see Malaria
Mayaro (viral) A92.8
Mediterranean A23.9 see also Brucellosis
familial M04.1
tick A77.1
meningeal see Meningitis
Meuse A79.0
Mexican A75.2
mianeh A68.1
miasmatic see Malaria
mosquito-borne (viral) A92.9
hemorrhagic A92.8
mountain see also Brucellosis
meaning Rocky Mountain spotted fever A77.0
tick (American) (Colorado) (viral) A93.2
Mucambo (viral) A92.8
mud A27.9
Neapolitan see Brucellosis
neutropenic D70.9
newborn P81.9
environmental P81.0
Nine-Mile A78
non-exanthematous tick A93.2
North Asian tick-borne A77.2
Omsk hemorrhagic A98.1
O'nyong-nyong (viral) A92.1
Oropouche (viral) A93.0
Oroya A44.0
pacific coast tick A77.8
paludal see Malaria
Panama (malarial) B50.9
Pappataci A93.1
paratyphoid A01.4
A A01.1
B A01.2
C A01.3
parrot A70
periodic (Mediterranean) M04.1
persistent (of unknown origin) R50.9
petechial A39.0
pharyngoconjunctival B30.2
Philippine hemorrhagic A91
phlebotomus A93.1
Piry (virus) A93.8
Pixuna (viral) A92.8
Plasmodium ovale B53.0
polioviral (nonparalytic) A80.4
Pontiac A48.2
postimmunization R50.83
postoperative R50.82
due to infection T81.40 Non-billable
posttransfusion R50.84
postvaccination R50.83
presenting with conditions classified elsewhere R50.81
pretibial A27.89
puerperal O86.4
Q A78
quadrilateral A78
quartan (malaria) B52.9
Queensland (coastal) (tick) A77.3
quintan A79.0
rabbit see Tularemia
rat-bite A25.9
due to
Spirillum A25.0
Streptobacillus moniliformis A25.1
recurrent see Fever, relapsing
relapsing (Borrelia) A68.9
Carter's (Asiatic) A68.1
Dutton's (West African) A68.1
Koch's A68.9
louse-borne A68.0
Novy's
louse-borne A68.0
tick-borne A68.1
Obermeyer's (European) A68.0
tick-borne A68.1
remittent (bilious) (congestive) (gastric) see Malaria
rheumatic (active) (acute) (chronic) (subacute) I00
with central nervous system involvement I02.9
inactive or quiescent with
cardiac hypertrophy I09.89
carditis I09.9
endocarditis I09.1
aortic (valve) I06.9
with mitral (valve) disease I08.0
mitral (valve) I05.9
with aortic (valve) disease I08.0
pulmonary (valve) I09.89
tricuspid (valve) I07.8
heart disease NEC I09.89
heart failure (congestive) (conditions in category I50.) I09.81
left ventricular failure (conditions in I50.1-I50.4-) I09.81
myocarditis, myocardial degeneration (conditions in I51.4) I09.0
pancarditis I09.9
pericarditis I09.2
Rift Valley (viral) A92.4
Rocky Mountain spotted A77.0
rose J30.1
Ross River B33.1
Russian hemorrhagic A98.5
San Joaquin (Valley) B38.0
sandfly A93.1
Sao Paulo A77.0
scarlet A38.9
seven day (leptospirosis) (autumnal) (Japanese) A27.89
dengue A90
shin-bone A79.0
Singapore hemorrhagic A91
solar A90
Songo A98.5
sore B00.1
South African tick-bite A68.1
Southeast Asia hemorrhagic A91
spinal see Meningitis
spirillary A25.0
splenic see Anthrax
spotted A77.9
American A77.0
Brazilian A77.0
cerebrospinal meningitis A39.0
Colombian A77.0
due to Rickettsia
africae (African tick bite fever) A77.8
australis A77.3
conorii A77.1
parkeri A77.8
rickettsii A77.0
sibirica A77.2
specified type NEC A77.8
Ehrlichiosis A77.40
due to
E. chaffeensis A77.41
specified organism NEC A77.49
Rocky Mountain A77.0
steroid R50.2
streptobacillary A25.1
subtertian B50.9
Sumatran mite A75.3
sun A90
swamp A27.9
swine A02.8
sylvatic, yellow A95.0
Tahyna B33.8
tertian see Malaria, tertian
Thailand hemorrhagic A91
thermic T67.01 Non-billable
three-day A93.1
tick
American mountain A93.2
Colorado A93.2
Kemerovo A93.8
Mediterranean A77.1
mountain A93.2
nonexanthematous A93.2
Quaranfil A93.8
tick-bite NEC A93.8
tick-borne (hemorrhagic) NEC A93.8
trench A79.0
tsutsugamushi A75.3
typhogastric A01.00
typhoid (abortive) (hemorrhagic) (intermittent) (malignant) A01.00
complicated by
arthritis A01.04
heart involvement A01.02
meningitis A01.01
osteomyelitis A01.05
pneumonia A01.03
specified NEC A01.09
typhomalarial see Malaria
typhus see Typhus (fever)
undulant see Brucellosis
unknown origin R50.9
uveoparotid D86.89
valley B38.0
Venezuelan equine A92.2
vesicular stomatitis A93.8
viral hemorrhagic see Fever, hemorrhagic, by type of virus
Volhynian A79.0
Wesselsbron (viral) A92.8
West
African B50.8
Nile (viral) A92.30
with
complications NEC A92.39
cranial nerve disorders A92.32
encephalitis A92.31
encephalomyelitis A92.31
neurologic manifestation NEC A92.32
optic neuritis A92.32
polyradiculitis A92.32
Whitmore's see Melioidosis
Wolhynian A79.0
worm B83.9
yellow A95.9
jungle A95.0
sylvatic A95.0
urban A95.1
Zika virus A92.5
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Related Index Terms
AnthraxCholecystitisMelioidosisMononucleosisTularemiaTyphusAll index terms starting with FIndex to Diseases and InjuriesICD-10-CM Code Lookup
Source: Centers for Medicare & Medicaid Services, FY 2026 ICD-10-CM Index to Diseases and Injuries release files, effective October 1, 2025 through September 30, 2026.
