Many drugs contain cathecholamine derivatives (local anesthetics, eye drops with neosynephrine, nasal vasoconstrictives).
Urticaria, eczema (oral absorption of pseudoephedrine), fixed drug eruption, scarlatin-like rash.
Acute conjunctivitis with eczema of the eyelids (neosynephrine containing eye drops).
Prick-tests and patch-tests with pseudoephedrine 1%, 5% in water or pet. (patch-tests).
Immediate hypersensitivity is exceptional.
Delayed contact hypersensitivity is more frequent.
Mechanism is unknown in toxic shock syndrome and in most rashes.
Cross-reactivity may exist among cathecholamine derivatives.
There are 2 types of derivatives:
- ephedrine, pseudoephedrine and norephedrine derived from a molecular structure of phenyl propanolamine type.These molecules have a very close structure and can cross-react.
- epinephrine and phenylephrine do not seem to cross-react with the first group. Thus sensitization to pseudoephedrine does not contra-indicate the use of eye drops containing neosynephrine and the use of epinephrine containing local anesthetics.