First thing you will have to do is to avoid tin or pre-packaged foods as they always contain a significant quantity of preservatives and additional elements. Try to eat fresh food like home made cuisine or fruits.
Consult your doctor and ask him/her the names of additives that caused this trouble. You should make a list of those elements. Sometimes, these additives have different names as they also carry their formula as name. Keep this list in your pocket all the time especially while going out.
If you cannot resist the temptation of packed food then best way to avoid any unforeseen trouble is to read its labels. Avoid if any of the additives is in your list.
You better check fresh items also as sometimes fruits or salads comprise additives or dyes that may cause trouble to those who are allergic to these elements.
Make first hand transaction. You should get your stuff direct from farmers’ market where all the eatables come from the field. Preservatives or additives are always injected by the exporters or dealers.
If you are having lunch/dinner in a restaurant, it is better to ask them about the additives in the food. Call the manager or chef and try to get a special/customised meal as it can really help you in avoiding any trouble. You can make a list of hotels and restaurants that serve additive-free food.
If you are invited by someone then inform the host about your allergy as it can save you from any unexpected trouble. Your family and friends should also have the complete information.
Always carry your medicine with you especially if you are travelling outside of your city. This will provide an instant treatment in case of any emergency.