As psoriasis is already caused by our immune systems attacking our own skin cells and causing damage it is logical that scratching will make it worse. Having said that I have also found my body fights off some of the medications I have been prescribed for my arthritis I can't take naproxen as it made my face break out red and patchy. Some antibiotics I react to as well it's whatever the medications are mixed with.
Problem is, that some scratching feels so good 😊 but can do so much damage!!!