Blisters on the elbows are not common with eczema. Questions I would have for you include: 1) Are these lesions itchy? 2) Does she develop blisters elsewhere? 3) How long has this been going on? There are many causes of skin blisters, including bug bite reactions, allergic skin reactions, infections, and the so-called blistering disorders, which are quite rare. Before preventive strategies or treatment can be recommended, your daughter obviously needs to be properly diagnosed. Have her evaluated by her pediatrician or a dermatologist.