Despite its effectiveness in treating psoriasis, Deu can cause adverse effects such as upper respiratory infections and herpes zoster, and is contraindicated in patients with severe hepatic impairment or latent tuberculosis infection.[7, 10, 12, 13] Therefore, developing transdermal formulations of TYK2 inhibitors is essential for psoriasis treatment with reduced systemic exposure, yet such formulations for Deu are currently unavailable. Here, TYK2 is linked to psoriasis.