Other commonly used allergens include citrus oils, mushroom oil, almond and other tree nut oils, and soy protein.
• Glues – Many glues and adhesives contain wheat. Be careful around stamps and envelopes since confirming the ingredients in those adhesives is difficult. Whenever possible, chose self-stick stamps and envelopes to avoid licking the adhesive.
You may want to create a master list of product categories that you use to help keep track of which products and brands are safe or are not safe because they contain known allergens.
About.com: Food Allergies