When you know that it's not because of something you just ate, check your mouthwash. Yeah, you read it right. Some mouth rinses and toothpastes contain zinc to help freshen breath and fight tartar; the mineral has also been found in dental adhesives. Too much of this can be toxic and you may experience feeling nauseous, dizzy and pain in the stomach. And if you're taking multivitamins containing zinc or eat zinc fortified cereal in addition to using zinc containing mouthwash or toothpaste, you can easily race past the recommended 8 mg a day. Try to avoid mouthwashes and toothpastes with this mineral. Read the labels and look for zinc citrate trihydrate.