A news report this month describes the anaphylactic death of a milk-allergic girl after using a toothpaste which unexpectedly contained milk-protein. Although the toothpaste container indicates that it contains an ingredient derived from milk protein and should not be used by patients with milk allergy, this was not noticed by the patient or her family. It is likely that most food-allergic patients and their families would not have thought to look for milk as an ingredient in toothpaste. It is very rare for a toothpaste to contain such a food protein.
In order for a food allergen to cause a potentially life-threatening anaphylactic reaction, it has to enter the bloodstream which is virtually always by ingestion. Although exposure to food allergens by inhalation or skin contact can cause some minor symptoms, it is exceedingly rare for such exposure to cause more serious reactions. This case highlights another potential route of exposure, mucosal. Mucosa or mucous membranes describe the lining of various body cavities including the mouth. Teeth brushing is known to allow substances from the mouth to enter the bloodstream, which is presumably how the milk protein in this toothpaste caused anaphylaxis in this child.
This case highlights the need for ongoing vigilance by food-allergic patients and their families regarding reading labels on any substance that enters the patient’s mouth, given the potential to enter the bloodstream and cause a life-threatening reaction. This includes not only more obvious substances such as foods and beverages themselves, but also less obvious substances such as toothpaste as in this case. Other examples of allergens being absorbed into the bloodstream from mucosal surfaces include latex from dental dams used in the mouth and gelatin-containing sponges used during surgery. Thus patients also need to inform medical and dental providers about their food and other allergies.
It should also be recognized that although a large number of excipients or inactive ingredients in medications are derived from food, in the vast majority of cases, they do not contain food protein or not enough food protein to provoke a reaction. For example, many influenza vaccines are grown in eggs but even severely egg allergic children are at no increased risk for a reaction to these vaccines. Thus, in addition to reading labels and asking questions to avoid an unexpected exposure to a food allergen, it is also important not to withhold medications and treatments that do not pose a risk.
This article has been reviewed by Andrew Moore, MD, FAAAAI