Scientists have developed a new toothpaste that shows potential to prevent severe allergic reactions in adults with peanut allergies.

An early-stage clinical trial tested whether 32 adults with peanut allergies could safely brush their teeth with the toothpaste, which contains trace amounts of peanut protein. The hope is that introducing small amounts of peanuts to the body over time will help the immune system get used to the allergen and reduce severe reactions.

Adults in the trial used the toothpaste once daily for about 11 months. At the end of the study, none of the participants experienced severe reactions or anaphylaxis — an allergic response often characterized by difficulty breathing, swelling in the throat, pale skin, blue lips, fainting or dizziness.

A summary of the results was presented Thursday at the American College of Allergy, Asthma and Immunology’s annual meeting in Anaheim, California. Although the trial focused on the safety of the toothpaste and did not test the effectiveness of the treatment in adults, the findings are an early indication that it could help prevent life-threatening allergic reactions in people with severe peanut allergies.

William Berger, the study’s lead author and a board-certified allergist, said the toothpaste should be easier to administer than injection treatments.

“People don’t like injecting themselves,” Berger said. With the toothpaste, he added, “patients do not have to do anything other than brush their teeth. We think it will provide better protection because the patient will be taking their treatment on a regular basis without any interruptions.”

The study participants were divided into two groups: 24 adults who used the toothpaste, and eight adults who used a placebo paste. Over about four months, the researchers gradually increased the dose of peanut protein in the toothpaste until participants were receiving the equivalent of about one-third of a peanut kernel, Berger said. The researchers instructed all participants to brush their teeth with the paste for two minutes a day, then spit it out.

The toothpaste, which doesn’t yet have a commercial name, is a product from biotechnology company Intrommune Therapeutics. When people brush their teeth with it, the peanut protein gets absorbed into their mouth. Over time, immune cells in the mouth should become desensitized to the allergen and people’s reactions to peanuts could become less severe.

The body “develops immunity to that allergen over time,” Berger said, though he noted the toothpaste is only intended to prevent a severe allergic reaction to an accidental exposure to peanuts, and does not serve as a cure to the allergy.

All but 3% of all participants continued using either the toothpaste or placebo for the 11-month trial. While 54% of participants who used the toothpaste experienced mild itchiness in the mouth and around the lips, Berger said, nobody dropped out of the study due to side effects.

Edwin Kim, director of the Food Allergy Initiative at the University of North Carolina, said the toothpaste could have an advantage over Palforzia, a powder approved by the Food and Drug Administration to treat peanut allergies in children ages 4 to 17. The powder needs to be refrigerated and mixed with foods like applesauce or yogurt.

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“Unfortunately, what we know with that type of treatment is that side effects including allergic reactions are actually pretty common,” said Kim, who wasn’t involved in the trial. “It’s already hard enough to be thinking about avoiding your allergen.”

More treatments could be on the horizon

Several more treatments for severe peanut allergies are being studied in clinical trials.

An October study that Kim led, published in The Journal of Allergy and Clinical Immunology, found that putting a small amount of liquid peanut extract under the tongue desensitized young children to their peanut allergy. By the end of the trial, almost 80% of participating toddlers could tolerate 15 peanuts without allergic symptoms.

A late-stage trial in May also showed that a “peanut patch” helped children ages 1 to 3 tolerate the equivalent of one to four peanuts by helping them absorb small doses of peanut protein through the skin.

While about 1 in 50 children in the U.S. have peanut allergies, a 2021 study found that approximately 4.6 million U.S. adults have the allergy, too. Another study from the same year found that U.S. adult peanut allergies have more than tripled over the past two decades, though the reasons for this trend are unclear.

Ruchi Gupta, founding director of the Center for Food Allergy and Asthma Research at Northwestern University, said it’s important to administer allergy treatments to children as early as possible because that’s when the body’s immune system is the most malleable.

Ideally, parents should get their child’s allergy treated in their first year of life, or as soon as it’s discovered, Gupta said. This gives the child the greatest opportunity to reverse the allergy or at least develop a strong tolerance.

“I think as people get older, [the allergy] becomes a little bit more set,” said Gupta, who wasn’t involved in the new research.

Now that the peanut-protein toothpaste seems safe for adults, Berger said, the next step is to test the paste’s safety and effectiveness among children. A pediatric trial involving 80 children between the ages of 4 and 17 is slated to begin next year, Berger said.

Berger said he hopes to submit the toothpaste for FDA approval within two or three years, which would require studying it in a larger group of volunteers first. If the toothpaste is ultimately approved, Berger expects it could be available via prescription rather than over the counter.