First of all, I think you have done an excellent job in looking up the literature in this regard and I can add nothing definitive to the information that you found. In actuality, I think that there is no "carte blanche" answer that would apply to all the distilled liqueurs in question. For example, gin, which is made from agricultural products, usually barley, is available in different flavors. In terms of the gin you specifically mentioned, Bombay Sapphire, the infusion is with a mixture of juniper, lemon peel, grains of paradise, coriander, cubeb berries, orris root, and almonds. On the other hand, Tanqueray London Dry Gin does not have nuts in it. It contains juniper, coriander, angelica, and liquorice. So, there would be no obvious risk in a nut-allergic patient drinking Tanqueray London Dry Gin. The grain itself, of course, presents no significant clinical cross-reactivity with nuts.
Another example of the variation of the contents of each liqueur is that Disaronno Originale Amaretto (as you mentioned), although it has a bittersweet almond taste, does not contain almonds or nuts. It is described as containing apricot kernel oil. In addition, it has 17 selected herbs and fruits. The exact herbs and fruits contained is not listed by the manufacturer, but they do state that this drink is nut-free. Thus, one cannot apply a carte blanche rule to each and every liqueur.
My opinion is that the risk is very small of a patient allergic to nuts reacting to a liqueur which contains the essence of nuts in a well-distilled product. However, unfortunately, the only way that you could know for sure would be to do an oral challenge to the liqueur. We have done oral challenges to alcoholic products previously, and they are not difficult to do; the only caveat of course is that the patient should have a driver to take them home.
In sum, the only way that I know of to answer your patient’s question is to look up, on the website of the dealers, the contents of any liqueur your patient wishes to ingest. If there is no nut product, there would be seem to be no risk of a reaction. If a nut product was contained, she should avoid that product, or alternatively, since I think the risk would be small, you could do an in-office oral challenge to small but gradually increasing amounts.
Thank you for your inquiry and we hope this response is helpful to you.
Phil Lieberman, M.D.