Scratching makes the condition worse by releasing more and more cytokines and antibodies. Once triggered, complex mechanisms in the body operate to cause the symptoms of atopic dermatitis. But histamine also damages tissue and thus continues the inflammatory process which produces the inflamed skin rash of atopic dermatitis. These rashes often become infected. Traditional therapies for atopic dermatitis include corticosteroids and antihistamines.
Corticosteroids are effective but have side effects that increase with chronic use.
And some classes of antihistamines cause excessive sedation. Cyclosporine is another immunosuppressant drug that works similarly to tacrolimus in preventing organ rejection. A large molecule, cyclosporine can't readily be absorbed through the skin. The development of topical tacrolimus was based on an unexpected discovery. However, the results of clinical trials to date show little systemic absorption.