Oxymel

Oxymel is a mixture of honey and vinegar, historically used as a medicine.
Its name is often found in Renaissance pharmacopoeiae in Late Latin form as either a countable or uncountable noun. As a countable noun, it is spelled variously as oxymellus and oxymellis, and
plural oxymeli and oxymelli.

Etymology and recipe

describes it thus:

Use

In the 1593 work Enchiridion chirurgicum, oxymel was recommended as part of a treatment for ophthalmia.
Because Latin was still used widely in medical prescriptions, it was still known by this name in Victorian times:

Modern use

Clinical trials involving oxymel have investigated its impacts on chronic medical conditions including obesity although low sample sizes and lack of data mean that more research is needed before drawing conclusions.