Patch testing can help to determine if you are allergic to specific components of personal care products; after you have been patch tested; your dermatologist will assist you with finding appropriate products. If your doctor has told you that you are sensitive or allergic to a specific substance, avoid products that contain that too. There are a wide variety of additional ingredients, usually preservatives, which can cause skin irritation or allergy, and it’s best to avoid them if you already have hand eczema. When in doubt, use plain petrolatum. It only has one ingredient.