Are there many complications with fifth disease?

No. Kids get a rash, mild fever, and/or mild cold symptoms. Adults get a rash, some joint aches, and/or joint swelling. Infected persons, with or without symptoms, mostly recover without complications and have immunity from re-infection. Complications can occur in persons with chronic anemia or immunosuppression. Occasionally, a woman infected in her first trimester may miscarry or have fetal anemia.
Yes. The main one is bone marrow aplasia-bone marrow does not make enough red blood cells.