Husband has been sitting on the same recliner for 10 years. this week he developed hives that itch on the back of his elbows and his bottom. cause?

Prob unrelated.: I greatly doubt that the itchy hives are from the recliner unless you have recently applied a solution, to which your husband may have become allergic, on the recliner. Try antihistamine first. If the problem continues, consult a derm/allergist. If you had indeed applied a new solvent to the recliner within days prior to the onset, remove it with a dishwater detergent