Hello Vicky, if you follow a gluten free diet this will help the body to absorb more nutrients which will in turn improve the immune system, as the digestive system is part of immunity - in other words a healthy diet (low sugar, no junk food etc) and plenty of green veg and fruit. My daughter and I always take the herb Echinacea at first sign of a slight sniffle, it almost always works - consult your GP before taking though. I drink a lot of water with a couple of slices of lemon, helps to keep detoxed. Honey as well is also very good as is pro biotic yogurt. Of course diet should be about 80% alkaline and 20% acid. Body cannot cope with being too acidic as this could cause many of the conditions which we are all trying to avoid. This post is not intended to replace any professional medical advice as we are all different - hope it helps in some way. Agree with previous posts that you must be assertive and explain to friends that you really need to avoid coughs and colds. Best wishes to everyone.