If you have flu symptoms, try this concoction to help you feel better:
lemon juice + honey + hot water
or, if you have a really sore throat, try this, which certainly doesn't taste any good:
lemon juice + honey + vinegar + hot water
If you have an upset or sensitive stomach as well, shu pu seems to do it favors.
but since I can't usually taste or smell anything when I'm sick, I just drink something hot. If it has to be tea, then it will probably be something that I don't like all that much normally.
(135 mentioned spearmint, which is nice when sick. There are some commercial blends of spearmint and lemongrass - I think Tazo sells one - that work well)