Background: Topical administration of ketoprofen to treat local subcutaneous pain significantly reduces gastrointestinal and cardiovascular adverse effects associated with oral delivery. However, this benefit must be weighed against the risk of photosensitisation/phototoxicity. Objective: To substantiate the safety and efficacy of topical ketoprofen delivery from a patch. Methods: Experiments were performed, and published information analysed, (a) to confirm the superior skin permeability and pharmacological activity of ketoprofen, and (b) to demonstrate the lower incidence of ketoprofen photosensitisation/phototoxicity when delivered from a topical patch. Results: Ketoprofen's photodegradation products were more photoallergic than the drug itself. The period postketoprofen treatment that skin should be protected from UV radiation (while the drug is cleared from the application site) was estimated. Conclusions: Photosensitisation to ketoprofen can be mitigated by a patch formulation, which protects the drug from direct UV exposure during skin application, and reduces the formation of even more photoallergic photodegradation products.