I sent him back a clip from a webpage on blue 1 dye allergies and it’s symptoms.

Potential Blue 1 Side Effects
Some studies suggest that Brilliant Blue FCF and Blue 2 may contribute to toxic effects. Symptoms of an allergic reaction due to Blue 1 or other food dyes may include:

Hives
Rashes
Itchy skin
Chest tightness
Flushing
Difficulty breathing
Severe headaches
Facial swelling
While most food dye allergic reactions are mild, some can become severe when not addressed.