Honey & ginger are normally used as food or food ingredient, moreover they are used as raw material for herbal & allopathic medicine. So they are not harmful at all. Second issue is their effectiveness in cough. If the cough has infectious origin then you may not get any positive result without antibiotics.You can use it along with antibiotics in infectious cough. In case of non infectious, dry, irritating cough they alone may be helpful.Take 2-3 inch knob of ginger, grind them to a paste, strain them to extract juice & add equal amount of honey. Use the mixture 2-3 times a day until cure. IMCI(Integrated Management of Childhood Illness)recommends warm water, tulsi leaf juice, lemon juice for simple cough & cold.