While it's difficult to get too much zinc from pumpkin seeds and other foods, signs of zinc toxicity include chills, fever, nausea, vomiting, loss of appetite, cramping, diarrhea and headache.

According to the Mayo Clinic, symptoms of a severe zinc overdose, usually found in people taking supplements, include chest pain, dizziness, fainting, shortness of breath and yellow eyes or skin.

The RDA of Zinc is 8 to 11mg daily.

Zinc
http://umm.edu/health/medical/altmed/supplement/zinc