How to identify and treat common bites and stings
A thorough history and physical are key to proper diagnosis and treatment following a patient’s encounter with an insect, arachnid, or other arthropod.
PRACTICE RECOMMENDATIONS
❯ Recommend that patients use an insect repellent, such as an over-the-counter formulation that contains DEET, picaridin, or PMD (a chemical constituent of Eucalyptus citriodora oil) to prevent flea bites. C
❯ Prescribe nonsedating oral antihistamines as first-line symptomatic treatment of mild-to-moderate pruritus secondary to an insect bite. C
❯ When indicated, refer patients for venom immunotherapy, which is approximately 95% effective in preventing or reducing severe systemic reactions and reduces the risk of anaphylaxis and death. C
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
Allergen-specific IgE antibody testing. These serum assays—typically, radioallergosorbent testing (RAST)—are less sensitive than venom skin tests. RAST is useful when venom skin testing cannot be performed or when skin testing is negative in a patient who has had a severe allergic reaction to an insect bite or sting. Serum IgE-specific antibody testing is preferred over venom skin testing in patients who are at high risk of anaphylaxis.52,53
Providing reliefand advanced care
Symptomatic treatment of mild bites and stings includes washing the affected area with soap and water and applying a cold compress to reduce swelling.54 For painful lesions, an oral analgesic can be prescribed.
For mild or moderate pruritus, a low- to midpotency topical corticosteroid (eg, hydrocortisone valerate cream 0.2% bid), topical calamine, or pramoxine can be applied,or a nonsedating oral antihistamine, such as loratadine (10 mg/d) or cetirizine (10 mg/d), can be used.14,55 For severe itching, a sedating antihistamine, such as hydroxyzine (10-25 mg every 4 to 6 hours prn), might help relieve symptoms; H1- and H2-receptor antagonists can be used concomitantly.54,55
Significant local symptoms. Large local reactions are treated with a midpotency topical corticosteroid (eg, triamcinolone acetonide cream 0.1% bid) plus an oral antihistamine to relieve pruritus and reduce allergic inflammation. For a more severe reaction, an oral corticosteroid (prednisone 1 mg/kg; maximum dosage, 50 mg/d) can be given for 5 to 7 days.54-56
Management of a necrotic ulcer secondary to a brown recluse spider bite is symptomatic and supportive. The size of these wounds can increase for as long as 10 days after the bite; resolution can require months of wound care, possibly with debridement. Rarely, skin grafting is required.27,28,31
VIT. Some studies show that VIT can improve quality of life in patients with prolonged, frequent, and worsening reactions to insect bites or stings and repeated, unavoidable exposures.55,56 VIT is recommended for patients with systemic hypersensitivity and a positive venom skin test result. It is approximately 95% effective in preventing or reducing severe systemic reactions and reduces the risk of anaphylaxis (see next section) and death.57 The maintenance dosage of VIT is usually 100 μg every 4 to 6 weeks; optimal duration of treatment is 3 to 5 years.58
Continue to: After VIT is complete...
