The placebo effect, because one group believes they are receiving a new prescription but they are actually taking the same prescriptions they always have. This can also be called a single blind experiment because the test subjects do not know which group they are in (or that there are two groups most likely), but the psychologist(s) know who is taking which prescription/who is in which group.
The crime scheme and suspect are very similar in the pattern meaning it is suspect number 2
Allergies. Allergies can trigger inflammations and dry skin.