cross sensitivity is defined as sensitivity to one substance that renders an individual sensitive to other substances of similar chemical structure . cross sensitivity has been reported commonly among various  lactam antibiotics and sulfonamides . for the diagnosis of cross sensitivity , various methods like prick test , oral challenge test is considered as the most reliable . due to broad antimicrobial spectrum , frequently reported adverse reactions with fluroquinolones are nausea , abdominal pain , diarrhea , dizziness , restlessness , headache , depression and somnolence or insomnia . . immediate type of reactions are more common than delayed type of reactions . frequently reported immediate hypersensitive reactions are urticaria , anaphylactic shock , rashes and erythema . ciprofloxacin and norfloxacin are the most common drugs causing hypersensitivity reactions , while levofloxacin is the least common with incidence of 1 per million population . however , we could not find a case of immediate hypersensitivity reaction with levofloxacin or case report of cross sensitivity between ciprofloxacin and levofloxacin . here with , we report a case of cross sensitivity between ciprofloxacin and levofloxacin for immediate type of hypersensitive reaction . seven years old male child ( 24 kg weight ) admitted in paediatric ward , sir takhtsinhji general hospital , government medical college , bhavnagar , gujarat , india with complaints of fever , headache , vomiting and abdominal pain for 7 days . fever was of high grade , intermittent and associated with chills , which was followed by colicky abdominal pain . he had a past history of similar attacks two times , at that time pain was relieved after oral treatment . various investigations like hemoglobin , total and differential wbc count , platelet count , esr , urine and stool examination were normal . as per surgical opinion conservative treatment was started with ciprofloxacin infusion ( 20mg / kg / day in two divided doses ) , inj . metronidazole ( 30mg / kg / day , in three divided doses ) , inj . five minutes after starting infusion of ciprofloxacin , patient developed itching followed by rashes at the site of infusion . on dermatological examination , reaction started from the site of injection and spread upward involving whole arm up to chest . infusion was stopped immediately and injection dexamethasone ( 0.5mg / kg ) was given along with injection chlorphenaramine maleate ( 0.1mg / kg ) . levofloxacin ( 10mg / kg / day ) was added in treatment in place of ciprofloxacin from next day under close observation . immediately after levofloxacin infusion , itching and rashes in arm appeared so , infusion was withdrawn . ceftriaxone ( 100mg / kg / day ) injection added in the place of fluoroquinolones along with metronidazole . it was moderate in severity according to modified hartwig and siegel 's scale and non preventable as per modified schumock and thornton scale . all fluoroquinolones have similar core structure ( 4-oxo-1 , 4-dihydroquinoline ring ) with fluorine atom attached at position 6 except , first generation quinolone , nalidixic acid . norfloxacin , a second generation fluroquinolone , is the result of replacement at c-7 methyl side chain with piperazine group , while replacement of n-1 ethyl group of norfloxacin with cyclopropyl group generates ciprofloxacin . levofloxacin , third generation flouroquinolone , has modification of piperazine group with methyl group at c-7 . although changes in position 1 , 7 and 8 generated different fluoroquinolones , core structure remains same . 54.5% immediate type of reactions to fluoroquinolones are ige mediated and occurs due to binding of ige to 7 position of core structure of fluoroquinolones . patient had a past history of two similar attacks , at that time he might be treated with fluoroquinolones , which may resulted in production of ige antibodies . as a result , treatment with fluoroquinolones this time might have caused the reaction . ciprofloxacin and levofloxacin have similar core structure ; this may be the reason for the cross sensitivity in this case . it is advisable to avoid other fluoroquinolones when hypersensitivity reaction detected to one and should be shifted to other class of antimicrobials . overall risk of adverse effects especially hypersensitivity reactions with fluoroquinolones is low but due to widespread use , such rare hypersensitivity reactions should be kept in mind . improvement in diagnostic tests like detection of ige antibodies , cellular tests and skin test may help in preventing such adverse drug reactions .
seven years old male child ( 24 kg weight ) diagnosed as a case of sub acute appendicitis treated with ciprofloxacin , immediately developed multiple erythmatous papules . 
 reaction subsided after withholding ciprofloxacin and treatment with dexamethasone and chlorpheneramine maleate . 
 it was developed again when treated with levofloxacin and subsided after withdrawal . 
 ige binding at 7th position of core structure of fluoroquinolones likely to be the mechanism . 
 as all the fluoroquinolones have similar core structure , hypersensitivity to one may have cross sensitivity to other fluoroquinolones . 
 it is advisable to avoid other fluoroquinolones and switch over to other group of antibiotics when hypersensitivity to one occurs .