Thank you for your inquiry.
It is true that alcohol can trigger anaphylactic events in some patients with indolent systemic mastocytosis. However, not all patients with this condition will react adversely to the ingestion of alcohol(1,2). The fact that your patient has ingested alcohol without difficulty makes it unlikely, but not impossible, that he would react to alcohol in the future.
Thus, I think that you would discharge your responsibility adequately by explaining this issue to him, citing that ideally one should avoid all potential triggers of an anaphylactic episode, but not all such triggers will produce events in every patient. It would be appropriate to metion to him the fact that he has ingested alcohol without difficulty makes it unlikely, but does not guarantee, that he will not react to alcohol ingestion in the future. I believe that you would have done due diligence by informing him of the risks involved.
I do not think that we have enough information regarding “the dose response curve” or the “threshold dose” of alcohol to advise him regarding the amount that he should ingest. It seems obvious that the greater the amount, the more likely the episode, but since we do not have definitive information, I would not broach this issue other than stating to him that it is likely (but not proven) that an episode would be more likely with the larger the amount he ingested.
Thank you again for your inquiry and we hope this response is helpful to you.
1) Neth J Med. 2005 Jul-Aug;63(7):244-9.Mastocytosis and adverse reactions to biogenic amines and histamine-releasing foods: what is the evidence?Vlieg-Boerstra BJ, van der Heide S, Oude Elberink JN, Kluin-Nelemans JC, Dubois AE.
2) Brockow K, Jofer C, Behrendt, Ring J. Anaphylaxis in patients with mastocytosis: a study on history, clinical features and risk factors in 120 patients. Allergy 2008;63:226-232
Phil Lieberman, M.D.