Potential causes of a metallic taste in the mouth that leads to nausea include upper respiratory infections, sinusitis or colds as well as cancer treatment such as chemotherapy or radiation, explains Cleveland Clinic. Poor oral hygiene produces a metallic taste when gum or teeth problems cause infections.
Common teeth and gum infections that produce a metallic taste include a tooth infection, periodontitis and gingivitis, according to Cleveland Clinic. Prescription drugs such as lithium, gout medication, cardiac medications and antibiotics can produce a metallic taste in the mouth that leads to nausea. Multivitamins with copper, zinc or chromium can also cause patients to test metal.