Wikipedia says side effects of zinc toxicity are nausea, vomiting, pain, cramps and diarrhea. I personally feel a background of nausea after taking zinc, and I once vomited when I took too much at once. Now I feel nauseous about taking zinc in the first place. I got headaches and lethargy even when I took a small amount of zinc for the first time after not taking it for a long time.
I normally never get headaches. I get tension in the middle of my forehead daily, but I rarely get what's known as a "headache". However, when I took zinc, it hurt even until the next day. Zinc seemed to no longer cause headaches when I took it for a few days (from what I remember, I wasn't willing to keep taking zinc recently until I got to the bottom of why it so reliably induces headaches), so I wonder if the body corrects the headache somehow or if it's due to too high a dosage at once.
I once made the mistake of combining black pepper extract, which increases potency of supplements, with zinc. The result was grueling lethargy, which would of rendered me dysfunctional if I had not realized higher zinc absorption caused it. It still gives me lethargy at a single dose. I once noticed that combining zinc with copper would prevent the lethargy, so this leads me to believe that it causes anemia by reducing copper, which has influence on respiration regardless of blood cell count. But I don't know where to get pure food-grade copper anyway. It didn't correct the headaches from zinc as long as they lasted.
Indeed, wikipedia says "A decrease in copper levels and hematological changes have been reported; however, those changes were completely reversed with the cessation of zinc intake.". People almost anemic could find out if zinc worsens their anemia by assessing facial complexion, and colors of the fingernails and under the eyelids. There was some clinical case of long-term zinc overdose when someone was taking it to treat acne, and they didn't know it was the zinc until they saw a doctor.
I normally never get headaches. I get tension in the middle of my forehead daily, but I rarely get what's known as a "headache". However, when I took zinc, it hurt even until the next day. Zinc seemed to no longer cause headaches when I took it for a few days (from what I remember, I wasn't willing to keep taking zinc recently until I got to the bottom of why it so reliably induces headaches), so I wonder if the body corrects the headache somehow or if it's due to too high a dosage at once.
I once made the mistake of combining black pepper extract, which increases potency of supplements, with zinc. The result was grueling lethargy, which would of rendered me dysfunctional if I had not realized higher zinc absorption caused it. It still gives me lethargy at a single dose. I once noticed that combining zinc with copper would prevent the lethargy, so this leads me to believe that it causes anemia by reducing copper, which has influence on respiration regardless of blood cell count. But I don't know where to get pure food-grade copper anyway. It didn't correct the headaches from zinc as long as they lasted.
Indeed, wikipedia says "A decrease in copper levels and hematological changes have been reported; however, those changes were completely reversed with the cessation of zinc intake.". People almost anemic could find out if zinc worsens their anemia by assessing facial complexion, and colors of the fingernails and under the eyelids. There was some clinical case of long-term zinc overdose when someone was taking it to treat acne, and they didn't know it was the zinc until they saw a doctor.