Combine berries and herbs with cold water in a pot and bring to a boil. Reduce heat and allow herbs to simmer for 30 minutes.
Remove from heat and mash berries in the pot. Allow to cool slightly.
Strain berries and herbs through a sieve, squeezing out all of the liquid; return to the pot.
Add honey and gently heat mixture for a few minutes. Do not allow honey to boil. Turn off heat and let cool.
If using alcohol, add and stir until well combined.
Bottle in a glass jar and store in the fridge.
Standard dose: ½ to 1 teaspoon for kids and ½ to 1 tablespoon for adults. If the flu does strike, take the normal dose every 2 to 3 hours instead of once a day until symptoms disappear.