Psoralen is a naturally occurring substance found in various plants, including limes, lemons, celery, parsley, figs, and cloves [1]. It belongs to a family of chemical compounds called furanocoumarins [2].
Medically, psoralen is used in a treatment called PUVA (psoralen + UVA) for conditions like psoriasis, eczema, vitiligo, and cutaneous T-cell lymphoma [2, 3]. PUVA therapy involves taking psoralen medication followed by controlled exposure to ultraviolet A (UVA) light.
Here's how it works: psoralen makes the skin more sensitive to UVA light. When UVA light hits skin cells containing psoralen, it triggers a reaction that slows down the growth of those skin cells [4]. In conditions like psoriasis, this helps to clear up the thick, scaly patches of skin.
It's important to note that PUVA therapy is not without its risks. Side effects can include nausea, vomiting, sunburn, and increased risk of skin cancer [5]. Because of these risks, PUVA therapy is generally only used when other treatments haven't been effective.