tarantula is a large spider which usually be found in tropical and subtropical areas , but recently has become as pets in worldwide ( 1 ) .
consequently , it is more likely that emergency physicians encounter with patients that hurt with these spiders .
they are nonaggressive arthropods that if to be forced to defend themselves , flick their needle - like abdominal hair at the target and may rarely bite ( 2 ) .
though tarantulas may look scary , most of their species are relatively harmless , just a few cases may be dangerous to humans ( 1 ) .
their attacks generally do not cause general manifestation , however there are some case reports in this regard ( 3 , 4 ) . here , an unusual presentation of tarantula bite was reported .
a 40-year - old man referred to the emergency department ( ed ) with severe colicky periumbilical pain , which was non - positional and radiated to both legs .
the patient did not have recent trauma history , except heavy lifting , and also any positive past medical history . on admission time
, tachycardia of 110/minute revealed a sinus tachycardia on 12 lead electrocardiogram ( ecg ) and hypertension of 220/110 mmhg in the right arm and 190/100 mmhg in the left arm . on physical examination ,
straight leg raising ( slr ) test did not aggravate the pain and all other systems were normal too .
with suspicion of large vessel insult abdominal sonography , chest radiography ( cxr ) and double contrast enhanced computed tomography ( ct ) were performed , all reported as normal .
after ruling out above - mentioned critical impressions , with attention to the history of heavy lifting , herniated disk was suspected so that magnetic resonance imaging ( mri ) was requested in which no abnormalities were found . during all these examinations , despite palliative treatments , the patient had severe pain without improvement .
unfortunately , the patient was discharged against medical advice and admitted again after 24 hours with right leg swelling and erythema . in this time , the patient was exposed and several bite - like sites were surprisingly found on his right leg .
tarantulas usually flick their hair at the target , so the most clinical presentations of biting are local allergic reactions including irritation , pruritus , edema , and erythema .
if the flicked hair takes place in eye , can result in redness and keratitis .
their bite usually sense as mild pain similar to a pinprick , but can cause severe pain , muscle spasms , local swelling , and numbness or even arthritis ( 3 , 4 ) . in spite of all above - mentioned , there is no properly documented case of permanent deficit or death following the tarantula bite ( 5 ) .
such severe symptoms almost always belong to other spiders like black widow spider ( 6 ) .
surprisingly , our case had some of these symptoms in spite of being bitten by tarantula .
therefore , we would consider that tarantula bite can mimic symptoms of black widow spider envenomation .
laboratory tests and imaging studies are not helpful for evaluation and management ( 7 ) .
in the case of tarantula bite , washing the site with soap and water and applying a cool compress or even an ice cube can reduce the local symptoms .
treatment in the ed is usually conservative and involves administration of antihistamines , corticosteroids , and analgesics ( 8) . although no specific treatment exists , it has been suggested that calcium supplements may be beneficial to relieve the muscle spasms ( 4 ) .
there is no report of recurrent or delayed reaction yet , so except for rare cases of anaphylaxis , all patients can be discharged after symptom resolution .
all authors passed four criteria for authorship contribution based on recommendations of the international committee of medical journal editors .
 tarantulas have recently become as pets in most parts of the world that increased the probability of encountering emergency physicians with patients hurt with these spiders . 
 their attacks usually do not cause general manifestation , however there are some case reports in this regard . here , 
 a 40-year - old man was reported who was referred to the emergency department with severe periumbilical pain that radiated to both legs and diagnosed as a victim of tarantula bite . 
 such symptoms usually are belonging to other spiders like black widow spider , but it seems that tarantula can mimic them in some cases , too . 
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