In May 2021, he complained of a sore throat without fever or cough. His
mother administered him one sublingual tablet of the over-the-counter
drug Lysopaine®, containing 20 mg
lysozyme hydrochloride and 1.5 mg cetylpyridinium chloride. A few
minutes after intake of the drug, he developed edema of the lips and
tongue, associated with dysphonia (Figure 1), without dyspnea, wheezing,
urticaria, or vomiting. His mother administered 5 mg of the oral
H1-antihistamine mequitazine and 20 min later, he took a 20 mg tablet of
prednisolone, because the symptoms persisted, before finally visiting
the emergency department. The initial examination showed a breathing
rate of 17/min, oxygen saturation of 98% in ambient air, a heart rate
of 93 bpm, and a blood pressure of 92/49 mmHg. He showed no wheezing or
dyspnea. He was administered another 20 mg tablet of prednisolone and
was monitored. Two hours later, he started vomiting and developed
abdominal pain, without dyspnea. He was administered 300 mg
intramuscular epinephrine (Anapen®) and the symptoms resolved within a
few minutes. He was then kept under
observation
for 8 h and subsequently discharged.
The allergy workup was conducted six weeks later. Skin prick-tests
(SPTs) were performed with Lysopaine® and egg white (ALK®). Lysopaine®
was crushed and mixed with a physiological saline solution and one drop
of the mixture used for prick-testing. Circulating sIgE against lysozyme
was measured using the ImmunoCAP System (Phadia, Uppsala, Sweden).
Results of the tests, including previous sIgE against egg white and
ovomucoid, are shown in Table 1 and Figure 2.