Polyethylene glycol

Polyethylene glycols (PEGs) are polymers of ethylene oxide (polyether) with different molecular masses from about 200 up to 5,000,000 Dalton and thus very different properties.PEGs and PEG relatives are widely used in medicine, cosmetics and industry. PRGs are marketed under different names depending on the size of the molecule:

• Macrogols (INN): PEGs used as ointments (see macrogol ointment) as well as laxatives in medicine. They are neither absorbed nor broken down by the skin or the intestines. Their molecular weight is used for their detailed description; e.g. macrogol 400 = molecular weight of 380-420. PEGs in cosmetics correspond to the macrogols in medicine. The term "macrogol 400" is synonymous with "PEG-9", a PEG consisting of 9 EO units.
• PEG Beeswax: Gel former in oleogels. The degree of ethoxilation is indicated by a hyphen after the PEG and can be about 3 to 20.
• PEG-Ester: are produced by the ethoxilation of carboxylic acids. It is used e.g. in shampoos.
• Polysorbates: These include surface-active substances such as Tween.
• PPG: Polypropylene glycols are produced from propylene oxide (PO) analogous to the PEG. They are used as a substitute for mineral and vegetable oils.
• Sodium Laureth Sulfate: Used mainly in shampoos and cleaning agents.
• Sodium Laureth Phosphate: Sodium Laureth-4 Phosphate is used in detergents and as emulsifier in creams.
• Higher molecular weight PEGs form moisture retaining films on the skin surface which only slightly influence the skin barrier layers due to the lack of penetration.

• Due to their good physical and chemical properties (good spreadability, water absorbency) polyethylene glycols are widely used as ointment base in cosmetics and dermatics (see macrogol ointment).
• Addition in medicines (injection fluids, intestinal rinsing solutions)
• in the industrial sector as solvent, lubricant and plasticizer
• in pencils, grease, water-based paints and polishes

The allergological relevance of polyethylene glycols is estimated to be very low. Only the low-molecular polyethylene glycols are able to penetrate through the skin at all, they are therefore most likely to be of allergological relevance. In a few individual cases type I and type IV reactions have been described.

If a contact allergy is suspected, the block Hermal Cooling Lubricants I, ointment bases and emulsifiers (polyethylene glycol ointment); test concentration 100 % can be used.

PEGs are sensitive to oxygen just like the structurally similar diethyl ether (the substance usually referred to as "ether"). In the presence of UV light they form highly reactive hydroperoxides, which were one of the causes of the so-called "Mallorca acne".

1. Borelli et al: Systemic immediate type reaction to Macrogol 4000, Allergo J 14, 39 (2005)
2. Dewachter et al (2005) Anaphylaxis to macrogol 4000 after a parenteral corticoid injection. Allergy 60: 705-706
3. Quartier S et al (2006) Allergic contact dermatitis to copolymers in cosmetics--case report and review of the literature. Contact Dermatitis 55:257-267. review