The preferred beverage for kiddush and havdalah, or other such mitzvot, is wine. In fact, according to a number of Rabbis, only wine (or grape juice) may be used for some or all of these mitzvot. Nonetheless, according to halachah, chamar medina, a local beverage which is considered important enough to be served socially instead of wine, is also acceptable when necessary.
Therefore, in a place where wine is not available, chamar medina may be used as a substitute for wine. In great need, or people who are not well and cannot drink wine, even if wine is available, one may make kiddush and havdalah on coffee or tea, which in our times is considered chamar medina.
Rav Yosef Yeshaya Braun, shlita, Badatz of Crown Heights, One Minute Halachah, #144, reprinted from crownheightsconnect.com
