Cheese with and without rennet still contains the proteins from the cow’s milk used to make the cheese. We therefore would advise you not to have it.
Halloumi is special. The milk (cow, sheep, or goat) used for its production is cooked in several steps for a longer time up to 90°C. During this process it loses some of its antigenicity which makes this cheese more tolerable for people with a milk allergy. So we test for Halloumi, in order to offer a possible additional alternative to patients with a milk allergy.