Key TakeawaysPolyethylene glycol (PEG) and polysorbate are additives in the COVID-19 vaccines. They protect the mRNA as it enters the human cell.PEG and polysorbate are found in many products including skincare, cosmetics, medications, and laxatives.Hypersensitivity to PEG leading to a severe allergic reaction has been reported, but it is not common.Allergic reactions to vaccines are not common, but they are possible. To be on the safe side, when you get in line to receive yourCOVID-19 vaccine, you will be asked if you are allergic toany ingredientsin the shot. While the ingredients in vaccines are safe, it is possible that someone might have sensitivities that could make them more likely to have an allergic reaction.What’s in the COVID-19 Vaccines?With the COVID-19 vaccines, experts point to a specific ingredient that, although rare, can trigger an allergic reaction in people who are sensitive to it: polyethylene glycol (PEG).What Is PEG?PEG, also called macrogol, is a lipid compound that acts as a solvent, thickener, softener, and moisture carrier in many common products including medications, toothpaste, shampoo, skincare, and laxatives.PEG is an additive in both the Moderna and Pfizer-BioNTech COVID-19 vaccines. It protects the mRNA as it is transferred into human cells.PEG in VaccinesPEG, as well as another compound additive called polysorbate (which is used in theJohnson & Johnsonvaccine), can trigger an immediate allergic reaction, though it is rare. The reaction may includeanaphylactic symptomsincluding rashes, shortness of breath, rapid heartbeat, and a decrease in blood pressure.The creation of the COVID-19 vaccines is the first time PEG has been used as an additive in a widely used immunization platform. That means that we do not have any data confirming that vaccines containing PEG have caused any severe allergic reactions. However, PEG and polysorbate have been noted as suspected causes of anaphylactic reactions to theModernaandPfizer-BioNTechvaccines.What’s the Risk of Having a Severe Allergic Reaction to the COVID-19 Vaccine?How Common is PEG Sensitivity?A 2016 study published inAnalytical Chemistryfound that about 7% of people who have been exposed to PEG from various products have a level of antibodies to the compound that is high enough to cause an anaphylactic reaction.In a presentation at the American Academy of Allergy, Asthma, and Immunology Annual Meeting,John Kelso, MD, a practicing allergist in the Division of Allergy, Asthma, and Immunology at Scripps Clinic and voluntary health sciences clinical professor at the University of California San Diego School of Medicine, said that “Even in the rare patient who is PEG allergic, we still don’t know if there is enough PEG in the vaccine to actually cause a reaction. It is certainly possible, but remains a speculation to date.”Severe allergic reactions to the COVID-19 vaccines do not happen often. In his presentation, Kelso reported that since COVID vaccine distribution began, only about 5 in 1 million people have reported an anaphylactic reaction to the vaccine, which he says is “really quite rare.”Fear of COVID-19 Outweighs Fear of Vaccine Side EffectsHow to Find Out If You’re Allergic to PEGAccording to allergists, there are a few ways to find out if you are sensitive to PEG. One of the easiest is to take a small amount of the over-the-counter laxative Miralax (polyethylene glycol 3350), which is mostly comprised of PEG, to see if you develop any symptoms of an allergy.If you have experienced an allergic reaction to any vaccine you’ve had in the past, make sure you talk to your healthcare provider before you get a COVID shot.Getting a COVID Vaccine If You Have SensitivitiesThe Centers for Disease Control and Prevention (CDC) recommends that people who have a known allergy to PEG do not get a COVID-19 vaccine that contains the compound, which rules out the Moderna and Pfizer-BioNTech vaccines. For people who are sensitive to PEG, the Johnson & Johnson vaccine could be an option.For people who are sensitive to polysorbate, the CDC recommends not getting a COVID-19 shot that contains the ingredient—in this case, the Johnson & Johnson vaccine. If you are not sure which vaccine is safe for you, talk with your doctor.People Who Talk to Their Doctors Are More Likely to Get VaccinesYou should also know that the CDC requires all vaccination sites have at least three doses of epinephrine, such asan EpiPen, on hand at all times. All sites also need to have staff who are trained to recognize the signs and symptoms of a severe allergic reaction and are prepared to administer treatment if necessary.What This Means For YouAllergic reactions to vaccines, including the COVID-19 vaccines, are rare. However, they are possible—especially if you have known allergies to certain ingredients or have had a reaction to a vaccine before.If you have a hypersensitivity to either PEG or polysorbate, talk to your doctor or allergist before receiving the COVID-19 vaccine.The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.

Key TakeawaysPolyethylene glycol (PEG) and polysorbate are additives in the COVID-19 vaccines. They protect the mRNA as it enters the human cell.PEG and polysorbate are found in many products including skincare, cosmetics, medications, and laxatives.Hypersensitivity to PEG leading to a severe allergic reaction has been reported, but it is not common.

Key Takeaways

Polyethylene glycol (PEG) and polysorbate are additives in the COVID-19 vaccines. They protect the mRNA as it enters the human cell.PEG and polysorbate are found in many products including skincare, cosmetics, medications, and laxatives.Hypersensitivity to PEG leading to a severe allergic reaction has been reported, but it is not common.

Allergic reactions to vaccines are not common, but they are possible. To be on the safe side, when you get in line to receive yourCOVID-19 vaccine, you will be asked if you are allergic toany ingredientsin the shot. While the ingredients in vaccines are safe, it is possible that someone might have sensitivities that could make them more likely to have an allergic reaction.

What’s in the COVID-19 Vaccines?

With the COVID-19 vaccines, experts point to a specific ingredient that, although rare, can trigger an allergic reaction in people who are sensitive to it: polyethylene glycol (PEG).

What Is PEG?PEG, also called macrogol, is a lipid compound that acts as a solvent, thickener, softener, and moisture carrier in many common products including medications, toothpaste, shampoo, skincare, and laxatives.PEG is an additive in both the Moderna and Pfizer-BioNTech COVID-19 vaccines. It protects the mRNA as it is transferred into human cells.

What Is PEG?

PEG, also called macrogol, is a lipid compound that acts as a solvent, thickener, softener, and moisture carrier in many common products including medications, toothpaste, shampoo, skincare, and laxatives.PEG is an additive in both the Moderna and Pfizer-BioNTech COVID-19 vaccines. It protects the mRNA as it is transferred into human cells.

PEG, also called macrogol, is a lipid compound that acts as a solvent, thickener, softener, and moisture carrier in many common products including medications, toothpaste, shampoo, skincare, and laxatives.

PEG is an additive in both the Moderna and Pfizer-BioNTech COVID-19 vaccines. It protects the mRNA as it is transferred into human cells.

PEG in Vaccines

PEG, as well as another compound additive called polysorbate (which is used in theJohnson & Johnsonvaccine), can trigger an immediate allergic reaction, though it is rare. The reaction may includeanaphylactic symptomsincluding rashes, shortness of breath, rapid heartbeat, and a decrease in blood pressure.

The creation of the COVID-19 vaccines is the first time PEG has been used as an additive in a widely used immunization platform. That means that we do not have any data confirming that vaccines containing PEG have caused any severe allergic reactions. However, PEG and polysorbate have been noted as suspected causes of anaphylactic reactions to theModernaandPfizer-BioNTechvaccines.

What’s the Risk of Having a Severe Allergic Reaction to the COVID-19 Vaccine?

How Common is PEG Sensitivity?

A 2016 study published inAnalytical Chemistryfound that about 7% of people who have been exposed to PEG from various products have a level of antibodies to the compound that is high enough to cause an anaphylactic reaction.

In a presentation at the American Academy of Allergy, Asthma, and Immunology Annual Meeting,John Kelso, MD, a practicing allergist in the Division of Allergy, Asthma, and Immunology at Scripps Clinic and voluntary health sciences clinical professor at the University of California San Diego School of Medicine, said that “Even in the rare patient who is PEG allergic, we still don’t know if there is enough PEG in the vaccine to actually cause a reaction. It is certainly possible, but remains a speculation to date.”

Severe allergic reactions to the COVID-19 vaccines do not happen often. In his presentation, Kelso reported that since COVID vaccine distribution began, only about 5 in 1 million people have reported an anaphylactic reaction to the vaccine, which he says is “really quite rare.”

Fear of COVID-19 Outweighs Fear of Vaccine Side Effects

How to Find Out If You’re Allergic to PEG

According to allergists, there are a few ways to find out if you are sensitive to PEG. One of the easiest is to take a small amount of the over-the-counter laxative Miralax (polyethylene glycol 3350), which is mostly comprised of PEG, to see if you develop any symptoms of an allergy.

If you have experienced an allergic reaction to any vaccine you’ve had in the past, make sure you talk to your healthcare provider before you get a COVID shot.

Getting a COVID Vaccine If You Have Sensitivities

The Centers for Disease Control and Prevention (CDC) recommends that people who have a known allergy to PEG do not get a COVID-19 vaccine that contains the compound, which rules out the Moderna and Pfizer-BioNTech vaccines. For people who are sensitive to PEG, the Johnson & Johnson vaccine could be an option.

For people who are sensitive to polysorbate, the CDC recommends not getting a COVID-19 shot that contains the ingredient—in this case, the Johnson & Johnson vaccine. If you are not sure which vaccine is safe for you, talk with your doctor.

People Who Talk to Their Doctors Are More Likely to Get Vaccines

You should also know that the CDC requires all vaccination sites have at least three doses of epinephrine, such asan EpiPen, on hand at all times. All sites also need to have staff who are trained to recognize the signs and symptoms of a severe allergic reaction and are prepared to administer treatment if necessary.

What This Means For YouAllergic reactions to vaccines, including the COVID-19 vaccines, are rare. However, they are possible—especially if you have known allergies to certain ingredients or have had a reaction to a vaccine before.If you have a hypersensitivity to either PEG or polysorbate, talk to your doctor or allergist before receiving the COVID-19 vaccine.

What This Means For You

Allergic reactions to vaccines, including the COVID-19 vaccines, are rare. However, they are possible—especially if you have known allergies to certain ingredients or have had a reaction to a vaccine before.If you have a hypersensitivity to either PEG or polysorbate, talk to your doctor or allergist before receiving the COVID-19 vaccine.

Allergic reactions to vaccines, including the COVID-19 vaccines, are rare. However, they are possible—especially if you have known allergies to certain ingredients or have had a reaction to a vaccine before.

If you have a hypersensitivity to either PEG or polysorbate, talk to your doctor or allergist before receiving the COVID-19 vaccine.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.

7 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Garvey LH, Nasser S.Anaphylaxis to the first COVID-19 vaccine: is polyethylene glycol (PEG) the culprit?Br J Anaesth. 2021;126(3):e106-e108. doi:10.1016/j.bja.2020.12.020

Science.Suspicions grow that nanoparticles in Pfizer’s COVID-19 vaccine trigger rare allergic reactions.

Yang Q, Jacobs TM, McCallen JD, et al.Analysis of pre-existing IgG and IgM antibodies against polyethylene glycol (PEG) in the general population.Anal Chem. 2016;88(23):11804-11812. doi:10.1021/acs.analchem.6b03437

Healio.Allergic reactions to COVID-19 vaccines rare, but ‘a lot of uncertainty’ remains.

Centers for Disease Control and Prevention (CDC).Information about COVID-19 vaccines for people with allergies.

Centers for Disease Control and Prevention (CDC).Interim considerations: preparing for the potential management of anaphylaxis after COVID-19 vaccination.

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