Terrence Steyer, M.D.
Chair, Department of Family Medicine
THREE MAJOR EFFECTS OF IFA STINGS:
1. Localized Irritation
80% of victims develop a local, non-allergic response to the IFA venom. In 8 to 24 hours, a characteristic small, blister-like vesicle forms which turns into a sterile pustule. The polysaccharide venom (99% piperidine) stings like pepper and attracts white blood cells to the site. The pustules rupture and scar in 3 to 7 days.
- Secondary infection may occur if the pustule is scratched or broken. Diabetics and others with circulatory disorders, including varicose veins and phlebitis, are at special risk for complications.
- Pustules require only ice or cold compresses, rest, and elevation of the extremity.
- An over-the-counter topical antihistamine lotion may help relieve itching and burning.
- Clean the vesicles with soap and water to prevent secondary infection.
- Do not break the pustule. If infection is suspected, seek medical attention.
2. Exaggerated Local Response
15% of victims develop an exaggerated local response which is characterized by allergic swelling at the site of the IFA sting. It can be caused by a single sting. Swelling may last for several days and may be accompanied by itching, redness, and pain. Since the swelling is due to allergy, not infection, antibiotics are not necessary. Patients in this category characteristically do not progress to the more severe allergic response - anaphylactic shock.
- Ice or cold compresses, rest, and elevation of the extremity to reduce swelling and pain.
- An over-the-counter topical antihistamine lotion may help relieve the itching, burning, and swelling.
- If symptoms persist, seek medical attention. Your physician may decide to prescribe an antihistamine and a trial of oral steroids.
3. Anaphylactic Shock
1-2% of victims develop generalized anaphylactic shock which is a life threatening, allergic reaction. This may occur within minutes of the sting and can occur the first or second time a person is stung. Adults are more susceptible than most children. Symptoms include swelling of the throat, face, eyes, unconsciousness, and difficulty in breathing.
If there is a Medical Emergency, Call 911
2. Prescription of two epinephrine self-injectors (Epi-Pen © ) for self administration (one may not be sufficient for a severe anaphylactic reaction)
3. Prompt referral to an allergist who will confirm the diagnosis and start the patient on a course of desensitization.