I'm not sure if there is anything OTC that can treat lupus rashes. Prevention... yes, with sunblock. If my sunblock fails me or I was in the sun too long (always try to prevent), my rashes are inevitable. My dermy has me on Locoid (topical steroid cream) to use on the spots to treat but you can only get that with a prescription.
Dx: IBS 1989, Diverticulosis 2004, Idiopathic Acute Colitis 2006, UCTD 2007, Localized Scleroderma 2009, Raynauds 2009
Meds: Plaquenil 400mg/day, Pred 2.5 mg/day (tapering), Methotrexate 10mg/week, Hydrocodone PRN, Flexeril PRN, Fiorinal PRN, Baby aspirin, Prenatal Multi, Vit E, B12, Fish Oil, Biotin, Calcium, Folic Acid