It is important to know that some topicals may actually hinder treatment. For example, some lotions contain UV absorbing ingredients similar to those used in sunscreens and may block much of the benefit of phototherapy treatment.
Other topicals and medications may photosensitize your skin. Watch out for lotions containing photosensitizing agents or essential oils such as lime, lemon, or orange. Such ingredients could cause an unexpected erythemal reaction when exposed to the ultraviolet energy delivered during a phototherapy treatment. In addition, coal tar, psoralens, and retinoids will consistently photosensitive your skin to UV light.  For a detailed list of photosensitizers, visit this link: https://www.daavlin.com/dont-see-red-know-these-photosensitizers/. We recommend speaking with your doctor about topicals and medications that may impact your phototherapy treatments.