are hives fluid filled
More Serious Skin Problems. The main feature distinguishing chronic hives from more serious skin disorders is whether the welts are filled with fluid. If the red bumps are itchy, inflamed, and filled with fluid, the condition is most likely hives. If theyâre hard and filled with other material besides fluid, and if after a skin test the lesions have a brownish color, thereâs most likely an underlying problem.