Overview
The doctor cocktail is a pre-prohibition era cocktail that traces in drink guides to as far back as 1917, when it appeared in Hugo R. Ensslin's Recipes for Mixed Drinks. As originally described the cocktail called simply for Swedish Punsch mixed with lime juice.
Like many older cocktails, many variations with the same name have been created over time, and drink guides sometimes listed multiple variations in the same book. The core of the cocktail consists of Swedish punsch and some variation of citrus (lime, lemon, or orange), with later variations skewing away from lime and also adding Jamaican rum.
Historical variations
After Ensslin's recipe, the doctor cocktail was also listed in Robert Vermiere's 1922 drink book where it dropped the use of lime, calling for 2 parts Swedish punsch, 1 part orange juice, and 1 part lemon juice (2:1:1 ratio).
Harry McElhone's guide Harry Ciro's ABC of Mixing Cocktails listed the ingredients as equal parts Swedish punsch, orange juice, and lemon juice (1:1:1 ratio), as did a 1927 Italian version (1:1:1 ratio). McElhone's guide however also carried an illustration for "The Recipe of the famous Dr. Cocktail" which called for 2/3 punsch and 1/3 lime juice, while suggesting that lemons could be substituted if one did not have limes on hand.
From Wikipedia (CC BY-SA 4.0).