On Dec. 14, the American College of Allergy, Asthma and Immunology (ACAAI) COVID-19 Vaccine Task Force issued guidance on the Pfizer vaccine, which had been authorized by the U.S. Food and Drug Administration (FDA) three days prior. In their guidance, the organization pointed out one specific ingredient that may cause problems for those with a history of allergies to it.ae0fcc31ae342fd3a1346ebb1f342fcb “The Pfizer-BioNTech COVID-19 vaccine should not be administered to individuals with a known history of a severe allergic reaction to polyethylene glycol (PEG), as it is a component of this vaccine that is known to cause anaphylaxis,” the ACAAI warned. Moderna’s vaccine, which wasn’t authorized by the FDA until Dec. 18, also contains this ingredient. So those with a PEG allergy may need to hold off on both vaccines until more research is conducted. The Centers for Disease Control and Prevention (CDC) echoes this concern, but without specifically calling out PEG. In its guidance, the CDC says that the Pfizer and Moderna vaccine should not be given to anyone with a history of severe allergic reactions to any ingredient used in the vaccines. According to Science Magazine, “some allergists and immunologists believe a small number of people previously exposed to PEG may have high levels of antibodies against PEG, putting them at risk of an anaphylactic reaction to the vaccine.” A 2016 study published in Analytical Chemistry found that as many as 72 percent of people have at least some antibodies against PEG, and about 7 percent have levels high enough that they could be at risk of an anaphylactic reaction. That having been said, as Science Magazine notes, allergic reaction to the COVID vaccines have only been documented in eight people. Nevertheless, an allergic response to PEG is not out of the question. According to the author of the Analytical Chemistry study, Samuel Lai, PhD, a pharmaco-engineer at the University of North Carolina Chapel Hill, people presumably develop these antibodies as a result of exposure to cosmetics and pharmaceuticals that contain PEG. Keep reading to find out what commonly used products have PEG as an ingredient, and if you’re worried about getting coronavirus, This Common Sensation Could Be a Sign You Have COVID, Doctors Warn. Toothpaste is something everyone uses daily, and it often contains PEG. According to Barbag Dental, a “basic brand of toothpaste contains sodium monofluorophosphate, glycerin, hydrated silica, water, sodium bicarbonate, PEG-12, sodium lauryl sulfate, sodium hydroxide, cellulose gum, carrageenan, sodium saccharin, calcium peroxide, and titanium dioxide.” The PEG-12 is what makes the toothpaste spreadable and adds a lubricated feel. And for more up-to-date information, sign up for our daily newsletter. Your shampoos are typically filled with all kinds of ingredients, including PEG. According to a 2015 study published in Toxicological Research, your shampoo could include a number of different PEGs, which all do different things. Some common examples include PEG-2, which acts as an anti-irritant; PEG-14, which helps with foam; and PEG-40, which acts as a lubricant. And for more questionable shampoo ingredients, If You See This on Your Shampoo Label, Toss It Immediately. If you take laxatives, you’re taking a PEG. According to the U.S. National Library of Medicine, most constipation treating medicines are PEG 3350. This medication, called an osmotic laxative, works by holding water with your stool. And for more potential vaccine complications, The CDC Is Warning You to Prepare For These COVID Vaccine Side Effects. According to Visions of Vogue, PEG is often used to “thicken products” that carry a lot of moisture, including moisturizing creams. This ingredient helps soften the skin and allows the cream to penetrate your skin better, which is why it’s often used. And for more on the future of the pandemic, Dr. Fauci Advises Against This One COVID Safety Measure.