A. Since eczema normally comes and goes and many children can go days or weeks with clear skin, it can be difficult to figure out what is triggering outbreaks of eczema like you are experiencing.
Although the role of food allergies and eczema is controversial, there is no good reason why a lactose free formula would help a child's eczema. If a child did have an allergy to a baby formula, it would likely be to either the milk proteins or soy proteins and not to lactose, which is a sugar.
The lactose free formula may have improved other symptoms, such as gas, fussiness, or diarrhea, but it is unlikely that it would have made his eczema better, so that may have been a coincidence.
If you really think that your baby's formula, including a milk based and soy formula, is making his eczema worse, then you might talk to your pediatrician about trying a hypoallergenic formula, such as Nutramigen or Alimentum. Allergy testing, using a blood test like the Immunocap, could be another option.
Keep in mind that many experts do not believe that food allergies are a big trigger for eczema though, so most parents should not go out of their way to restrict their child's diet without talking to their pediatrician first. Of course, if your child's eczema gets worse every time you give your child something to eat or drink, then it likely is a trigger for him and you should avoid it and talk to your pediatrician about food allergies.
And some kids do have both food allergies and eczema, but surprisingly, they don't seem to affect each other.
You could also see your pediatrician and review our guide to eczema to make sure you are doing everything you can to control and prevent your child's eczema by avoiding triggers and using moisturizers and topical steroids, etc.
Effective therapy of childhood atopic dermatitis allays food allergy concerns. Thompson MM - J Am Acad Dermatol - 01-AUG-2005; 53(2 Suppl 2): S214-9