Itching & hives for 3 wks. taking benadryl (diphenhydramine) & synthroid. cut out sunscreen, nuts, soy, tomatoes, vitamins, switched laundry det. no relief. now what?

Hives: Hives are an allergic reaction. There are many possible causes of hives-foods, medications, infections, inflammatory or autoimmune conditions. Did you start any new meds, supplements, foods, etc? Recent onset hives, if there is no apparent cause, are treated with antihistamines. Hives lasting > 6 weeks need a workup to look for causes. Please see your dermatologist right away for evaluation.