Well sometimes even a cold could be dangerous and you should see the doctor first.
But if you want to use magic, then use herbs (thyme, chamomile, calendula, elder lat.-sambukus, raspberry,), also helps lemon, ginger and garlic. Make hot teas and lay down in bed.
But do your work and research every herb before giving to your friend!
And using kitchen witchery - you also can enchant your teas or food for healing.