Allow me to express my opinion regarding zinc poisoning related to excessive usage of any dental adhesive containing zinc.
Our bodies need zinc to function properly but, like everything else we ingest, it must be done in moderation according to specific guidelines. The Recommended Dietary Allowance of zinc varies, but generally, the recommended daily allowance for zinc is 11 mg per day for men and 8 mg per day for women, respectively; however, a zinc dose of 40 milligrams is approved safe to use by FDA and a zinc dosage more than this can pose certain risks. Fixodent has a very low level of zinc, around 17 milligrams in each gram of paste.
The truth of the matter is that only about 30% of the zinc that you intake can get absorbed by your body. The amount of zinc that an average denture wearer would swallow from normal use of denture adhesive would be less than the zinc in almost all daily vitamin supplements, and about the same as the amount of zinc you would get from eating six oz. of beef.
If you use the recommended amount stated on the package, research shows that the amount of zinc an average user absorbs from Fixodent or Poligrip is approximately 2 mg. Where the cases of zinc toxicity come from are the users who were using 2 to 3 tubes of adhesive a week! A 2.4 oz tube of adhesive should last at least 7 to 8 weeks, while a 1.4 oz tube should last at least 4 to 5 weeks. This product should not be used more than once a day.
Too much zinc supplement will likely interfere with the metabolism and absorption of other essential minerals in your body, most especially iron, magnesium and copper reduce your body's immune function, affect your chemical balance in your brain, and reduce your HDL (good cholesterol) level.
Oral zinc sulfate supplements can also cause side effects such as stomach upset, heartburn and nausea. Rare side effects have also been reported and these include fever, sore throat, mouth sores, weakness and fatigue.
You mentioned problems such as bowel obstruction and rectal bleeding. Neither of these have been mentioned under zinc side effects in any of my research but, they ARE serious medical conditions that require immediate treatment!
I am hoping you have a strong and open relationship with your Primary Care Physician and that you will discuss your concerns with him/her as soon as possible!
If you decide to continue using denture adhesives, please know that they are completely safe when USED AS DIRECTED!