There are many remedies for a cough in my article http://is-it-a-cold-or-allergy There are many natural supplements that have antibacterial properties, including olive leaf, and oil of oregano. The dosages and strengths are listed in my article for each supplement. Elderberry liquid is an effective supplement, as it quiets the cough, and increases immunity. Zinc lozenges also work very well, as they kill the virus, or bacteria in the throat where it starts. Do not exceed 100mg per day of zinc, as this will lower immunity, not raise it. Other recommendations include a good daily multivitamin, containing zinc and D3, such as Vitafusion multi-vite adult gummies. He may also want to do a breathing treatment, to loosen the mucus, in the chest. Bring a pan of water to a boil, place pan on a heat safe surface. Place a towel around the head and pan. Breathe in steam, as you breathe in the steam it will loosen the mucus. When you cough up any phlem, do not swallow, spit it out, into a kleenex, and flush. Do not leave laying around, as it may spread the germs to others. Vicks vapo rub placed on the chest before bed time will also loosen mucus.