Final answer:
PUVA therapy is a medical treatment that combines a photosensitizing drug called psoralen with UVA light exposure. The therapy works by forming cross-links between psoralen and DNA molecules, preventing abnormal skin cells from multiplying and reducing symptoms of skin conditions.
Step-by-step explanation:
PUVA therapy refers to a medical treatment that combines a photosensitizing drug called psoralen with ultraviolet A (UVA) light exposure. Psoralen is either applied topically or taken orally, and it makes the skin more sensitive to UVA rays. When the affected skin is exposed to UVA light after psoralen administration, it helps to treat various skin conditions such as psoriasis, vitiligo, and eczema.
This therapy works by the psoralen molecules entering the cells of the skin, and when activated by UVA light, they form cross-links or bonds with the DNA molecules. These cross-links prevent the abnormal skin cells from multiplying and growing, thus reducing the symptoms of the skin condition.