Sodium fluoride and triclosan are the two toxic chemicals in toothpaste that, when eaten in excess, can lead to symptoms of an overdose such as vomiting, diarrhea, convulsions, trouble breathing, reduced heart rate, heart attack, and more (via Mount Sinai). While this may sound unnerving, the National Capital Poison Center emphasizes that non-prescription toothpaste products do not contain high concentrations of fluoride, but only enough to keep our teeth healthy and strong. So little, in fact, that a child would have to consume several tubes of toothpaste to be at risk for serious health outcomes (via Jackson Smiles Family Dentistry).
To get even more specific, researchers from a 2017 scientific review published in the Iranian Journal of Basic Medical Sciences noted that a child or adult would have to consume 5 milligrams of fluoride per kilogram of body weight (approximately 2.2 pounds) to reach toxic levels. Furthermore, children would have to ingest at least 16 milligrams of fluoride per kilogram of body weight for toothpaste consumption to potentially be fatal. For adults, the lethal amount of fluoride stands at 32 milligrams per kilogram of body weight. Because you’ll only find approximately 1.3 milligrams of fluoride in one dollop of toothpaste, knowing these numbers may help ease any fears around toothpaste consumption (via AutoBrush).