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Spider Envenomation, Tarantula: Treatment & Medication
Updated: May 7, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Prehospital Care
- Capture the offending arachnid for identification if it is possible to do so safely.
- Begin supportive therapy for patients who are having a rare allergic reaction or anaphylaxis.
- Following ocular exposure, place a protective shield over the eyes to prevent the patient from rubbing the eyes and possibly driving hairs deeper.
Emergency Department Care
A patient with anaphylaxis or allergic reaction requires prompt supportive care and attention to the ABCs.
In patients with severe reaction, establish an intravenous line, provide supplemental oxygen, and place them on a cardiac monitor.
- Skin
- Protect areas of localized dermatitis and allergic reactions with appropriate local wound care, including wound cleansing and ice to decrease inflammation.
- Determine tetanus immunization status and provide prophylaxis as needed.
- Treat pruritus and erythema with antihistamines and corticosteroids.
- Administer parenteral or enteral analgesics to relieve severe pain.
- Eye
- Ocular injury caused by tarantula hairs can be complicated and requires ophthalmologic consultation.
- After initial evaluation, patients should be treated with a topical broad-spectrum antibiotic.
- Topical steroids are required for patients with panuveitis or keratoconjunctivitis; they should be prescribed only after consultation with an ophthalmologist.
- As with skin contact, tetanus prophylaxis is indicated when the eye is involved.
Consultations
Patients can develop long-term inflammatory changes in the eye exposed to tarantula hairs, and definitive diagnosis of retained hairs cannot always be made by routine ED slit-lamp examination. Consulting an ophthalmologist is mandatory in such exposures.
Medication
No existing medications are specific to treat tarantula injuries occurring in the United States. Medical therapy is directed mainly at symptom relief.
One species of the funnel web spider (Atrax robustus) of Australia produces highly toxic venom that is neurotoxic and potentially fatal. Antivenom specific to Atrax has been developed and is used in Australia.
Antihistamines
Prevent but do not reverse histamine-mediated responses, particularly in smooth muscle of the bronchi, GI tract, uterus, and blood vessels. Prevent histamine responses in sensory nerve endings. Commonly used for temporary relief of symptoms caused by allergic conditions.
Diphenhydramine (Benadryl)
Competes with histamine for cell receptor sites on effector cells; has anticholinergic (drying) and sedative adverse effects.
Adult
25-50 mg PO/IV/IM q6-8h; not to exceed 400 mg/d
Pediatric
5 mg/kg PO/IV/IM divided qid; not to exceed 300 mg/d
Potentiates effects of CNS depressants
Documented hypersensitivity; syrup form only contraindicated with medications that cause disulfiramlike reaction
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Caution in patients with exacerbation of urinary tract obstruction, angle-closure glaucoma, peptic ulcer, and hyperthyroidism
Cetirizine (Zyrtec)
Forms a complex with histamine to block H1-receptor sites on target cells in blood vessels, GI tract, and respiratory tract.
Adult
5-10 mg PO qd
Pediatric
Neonates: Not recommended
<2 years: Not established
2-5 years: 2.5 mg PO qd
>6 years: Administer as in adults
Potentiates effects of CNS depressants
Documented hypersensitivity; neonates; premature infants; breastfeeding mothers
Pregnancy
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Precautions
Hepatic or renal dysfunction; doses >10 mg/d may cause drowsiness
Corticosteroids
Modify the body's immune response to diverse stimuli. Suppress the migration of polymorphonuclear (PMN) leukocytes and reverse increased capillary permeability, reducing inflammatory processes. Can cause profound and varied metabolic effects.
Prednisone (Deltasone, Sterapred, Orasone)
Has potent antiinflammatory effects in disorders of many organ systems.
Adult
5-60 mg/d PO; usual dose is 40 mg/d PO for 5 d
Pediatric
0.1-2 mg/kg/d PO or divided tid; usual dose is 2 mg/kg PO in one dose on day 1, then 1 mg/kg/d PO or divided tid for 5 d
Decreases effects of salicylates and toxoids (for immunizations) when administered concomitantly; effects decreased by phenytoin, carbamazepine, barbiturates, and rifampin
Documented hypersensitivity; viral, fungal, or tubercular skin lesions
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Hyperthyroidism, osteoporosis, cirrhosis, nonspecific ulcerative colitis, peptic ulcer, diabetes, myasthenia gravis
Ophthalmic agents
Used for inflammatory conditions in which corticosteroids are indicated and risk of infection exists.
Neomycin, polymyxin B and hydrocortisone (Cortisporin)
Hydrocortisone suppresses inflammatory response. Because it also may inhibit body's defense mechanism against infection, a concomitant antimicrobial drug may be used, giving rationale for combination. Anti-infective components are included to provide action against specific susceptible organisms.
Adult
Ointment: Apply thin layer to cover lesion qd/qid
Solution: 1-3 gtt in affected eye q1-2h while awake
Pediatric
Administer as in adults
None reported
Documented hypersensitivity; viral infections
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Extended use can lead to resistant infections and thinning or atrophy of the skin
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| Overview: Spider Envenomation, Tarantula |
| Differential Diagnoses & Workup: Spider Envenomation, Tarantula |
 Treatment & Medication: Spider Envenomation, Tarantula |
| Follow-up: Spider Envenomation, Tarantula |
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References
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Further Reading
Keywords
tarantula, tarantula envenomation, spider bite, eye injury, hairy spider, poisonous spider, Theraphosidae, Orthognatha, Theraphosa blondi, Aphonopelma, Grammastola, arachnophobia, spider envenomation, Chilean rose tarantula, tarantula hairs
