The standard approach to this sort of question is to indicate that skin testing is generally not helpful as we see so many false positives due to the known mast cell de-granulating properties of opiates.
Volume 31, Issue 7, pages 1014–1020, July 2001
Background: The value of skin prick testing in opiate-sensitive individuals is uncertain as opiates cause non-specific weals by direct degranulation of mast cells.
Objective: To define whether skin prick test (SPT) responses to opiates in opiate-sensitive individuals are different to those seen in the normal population and to describe the clinical characteristics of this group of subjects.
Methods: The SPT responses of eight opiate-sensitive subjects to morphine 10 mg/mL, pethidine (meperidine) 50 mg/mL and papaveretum 15.4 mg/mL at four different concentrations (undiluted, 1/10, 1/50 and 1/100) were compared with the responses of 100 (32 atopic) non-opiate-sensitive control subjects. Four of the opiate-sensitive subjects had a clinical history of asthma, rhinitis or urticaria on occupational exposure to morphine. One subject developed urticaria with codeine, one developed urticaria and asthma with morphine and diamorphine and two subjects reacted to intravenous papaveretum with anaphylaxis or urticaria. Five out of the eight cases had opiate sensitivity confirmed by single-blind placebo-controlled oral challenge.
Results: Skin prick tests to all three opiates were not significantly different when the eight opiate-sensitive subjects were compared with either the entire normal control group or the subgroup of 47 definite opiate-tolerant controls that had previously received opiates for clinical indications. Furthermore, there were no significant differences in size of opiate SPT responses between atopic and non-atopic control subjects. In the control subjects, there was a positive correlation in SPT weal size between the three opiates.
Conclusion: Skin prick testing is not useful in the diagnosis of opiate sensitivity and placebo-controlled challenge should be considered.
Additionally, the presence of purely subjective symptoms would reassure us that an outpatient graded challenge is appropriate. We would obtain a baseline spirometry with re-assessment should he develop shortness of breath. If rhinolaryngoscopy is available, that may also be of value should the patient develop the same tight throat symptom.