A polyethylene glycol (PEG) allergy is an immune system response to polyethylene glycol, a synthetic compound found in numerous products. Although PEG is widely used in various applications, allergic reactions to it are uncommon. When they do occur, these reactions can range from mild discomfort to severe, life-threatening responses.
Understanding Polyethylene Glycol (PEG)
Polyethylene glycol (PEG) is a synthetic polymer derived from petroleum. It is a versatile substance, distinguished by its water solubility, allowing it to blend effectively with water-based ingredients. It is generally considered non-toxic, inert, and versatile.
Its physical form varies from liquid to waxy solid, depending on its molecular weight, indicated by a number such as PEG 400 or PEG 3350. PEG serves multiple purposes, often as an inactive ingredient (excipient) in formulations, but also as an active component in some laxatives. Its versatility makes it a common additive in many products.
Recognizing Symptoms of a PEG Allergy
Allergic reactions to PEG manifest rapidly and can be severe, often progressing to anaphylaxis. Common skin symptoms include hives (urticaria), swelling (angioedema), generalized itching, and flushing.
Respiratory distress can include wheezing, shortness of breath, difficulty breathing, chest tightness, bronchospasm, or a persistent cough. Gastrointestinal issues like nausea, vomiting, diarrhea, and abdominal pain are also reported. More serious systemic reactions include feeling faint or dizzy from a sudden drop in blood pressure, and in extreme instances, cardiac arrest.
Common Products Containing PEG
PEG is found in a wide array of products. In pharmaceuticals, PEG is found in many medications. It is an ingredient in laxatives (e.g., Movicol, MiraLax), bowel preparation solutions, and certain steroid injections. Other medicines, including painkillers, antibiotics, antacids, and suppositories, also contain PEG. Notably, PEG is present in some vaccines, including mRNA COVID-19 vaccines.
Beyond medicine, PEG is used in cosmetics and personal care items. It is found in creams, lotions, shampoos, hair products, hand soaps, toothpaste, and mouthwash. In these applications, PEG functions as a humectant (to retain moisture), an emollient (for skin softening), a thickening agent, or an emulsifier. PEG is also a food additive (e.g., preservative, thickener) and appears in industrial products like household detergents, polishes, and bone cements.
Diagnosis and Management of PEG Allergy
Diagnosing a PEG allergy begins with a thorough review of medical history, noting any repeated, immediate severe reactions to PEG-containing products. Allergists may then conduct skin prick tests (SPT) using diluted PEG solutions. These tests must be performed under medical supervision due to the potential for systemic reactions. If skin prick tests are negative but suspicion remains, intradermal tests (IDT) may be considered, though these also carry a risk of systemic reactions. The detection of anti-PEG IgE antibodies is another method, though often used as a research tool.
Managing a confirmed PEG allergy involves strict avoidance of all PEG-containing products. Careful reading of product labels, looking for “PEG” or “macrogols,” is essential. Inform all healthcare providers (doctors, nurses, pharmacists, dentists, anaesthetists) about the allergy.
For individuals prone to severe reactions, carrying emergency medication, such as an epinephrine auto-injector, is advised. Wearing a medical-alert bracelet can provide crucial information in an emergency. A specialist allergist can offer tailored advice and a management plan.