Can a milk allergy cause acne?

Less likely: Depending on how old someone is, a true milk allergy can cause eczema-like rash, bloody diarrhea, hives, vomiting, difficulty breathing, facial swelling, cough, wheeze, abdominal pain, lip swelling, etc. Acne in young infants is due to leftover maternal hormones, and acne in preteens, teen, and young adults is due to puberty related changes in hormone levels and skin. Your doctor can see what's needed.

Yes possibly: You are more likely to have intestinal / stomach complaints as well as possible eczematoid rashes if you have milk allergy.