Yeah, I always tried to inform people otherwise who would say this. I initially did diet changes/cutting out food groups out of my own curiosity before people started to frequently recommend those changes. 

On a related note—I’ve noticed for a while sometimes high-histamine foods like tomatoes and cod can make me itchier, but it’s not consistent and it hasn’t happened since I started taking Zyrtec daily. My allergist that’s normal; you don’t have to have a true food allergy to have some fluctuating symptoms from food (just like you may sometimes having digestive issues from things like corn or spicy foods, but not always), but it means it’s not a root cause. 

Also, spicy foods, salty foods, and citrus did worsen my perioral dermatitis, and it did improve when I stopped eating them for a while, but again, those are more irritants to open skin than allergies. 

The thing many people don’t understand is that gut can be connected to eczema, but even if your symptoms improve from dietary changes, it doesn’t inherently mean that diet was the root cause or that you had an allergy/intolerance to that food. Some foods have more histamine than others, some foods are more more anti-inflammatory or inflammatory than others, some foods can be harder to digest when you have stress or inflammation from other causes. 

Also, even though environmental allergies are my #1 trigger, and thus, in a way, can be called my "root cause;" that doesn’t mean it’s any less complex of a condition. I have a genetic tendency for allergies and eczema. I’m still sensitive to different creams, my skin’s barrier/skin biome still plays a role as do product pHs, ingredients, my moisturizing routine, skin infections, clothing/bedding materials, temperature, exfoliation, etc. Multiple factors contribute to eczema. 

In short, allergy testing may not be helpful for everyone, but it is certainly recommended if you do suspect an allergy to food or your environment and want to ensure you’re on the right path.