Is zinc dangerous at to high quantity?

Yes.: You can have zinc toxicity if you ingest too much. It sometimes happens when you use zinc-containing denture cream for long periods of time. Also if you're taking zinc supplements after bariatric surgery or for wilson's disease, then there's a chance of getting too much. Data is still out on zinc for colds, but using it short term (few days) shouldn't put you at dangerous levels.

Zinc Toxicity: The recommended dietary allowance (rda) for zinc in adults is 11 mg for men and 8 mg for women. Zinc toxicity from high zinc intake can occur in both acute and chronic forms. Acute adverse effects include gastrointestinal disturbances and headaches. Chronic effects include reduced immune function, altered iron function, and reduced high density lipoprotein (HDL) levels.