You can also make a tea from the herb itself. These herbs are the traditional Chinese approach to colds, flu and other viruses. Reviewing the research, I'm persuaded that they have real antiviral benefits. When I feel a cold or flu coming on, I mix honeysuckle and forsythia with lemon balm tea, which also has antiviral action. I find a hot tea combination of the three herbs especially nice just before bed.
Onion is a close relative of garlic and contains many similar antiviral chemicals.
One old folk remedy for colds recommends steeping raw onion slices overnight in honey, then taking the resulting mixture at intervals like a cough syrup. Of course, you could also simply use more onions in cooking whenever you have a cold. Commission E, the body of experts that makes recommendations about herbs to the German government, endorses aniseed as an expectorant for getting rid of phlegm. In large doses, it also has some antiviral benefits. You can make a tea by steeping one to two teaspoons of crushed aniseed in a cup or two of boiling water for 10 to 15 minutes.