In personal care items (lubricants), PG may be used as a humectant, solvent, preservative, or flavor carrier. It increases lubricity, keeps the mucosal lining moist, and to prevents lubes from drying out on the shelf over time. It also helps bind ingredients together that are otherwise immiscible.

Propylene Glycol

The two most common names for PG are propylene glycol and propanediol.

The synthetic formulation, Propanediol (1,2), is made from petroleum. The natural formulation, Propanediol (1,3), is made from corn sugar. Both formulations are clear liquids with no odor, no taste, and an oily, rather than syrupy, consistency.

Polypropylene Glycol

PPG may be referred to as polypropylene glycol, polypropylene oxide, or PPG diol. It should not be confused with polyethylene oxide (PEO) or polyethylene glycol (PEG).

PPG is not a common lubricant additive but is frequently found in other personal care products.

Propylene glycol is sometimes confused with ethylene glycol, polypropylene glycol, and polyethylene glycol (polyethylene oxide). Ethylene glycol is the sweet tasting ingredient in anti-freeze and is toxic to animals and humans. Propylene glycol is sometimes used as an additive in certain antifreezes but has no taste and is not toxic at low levels.

As with all other lubricants, fisters ignore acceptable use standards published by manufacturers, the FDA, the EFSA, and the World Health Organization (WHO). For PG, the WHO recommends a maximum intake of 25 mg/kg (11.4 mg/pound) per day. Based on a density of 1.04 g/mL, this translates to about 2 mL or a half teaspoon of use per day. In a single session, fisters may be exposed to 500 times that amount.

PG is hypo-osmolaric and pH neutral; however, many lubes that use PG as an ingredient are actually hyper-osmolaric and outside normal pH values. Hyper-osmolaric and hypo-osmolaric substances can cause cell damage or death; limited studies with PG-based lubes on rectal tissue are available to confirm any short term or long term damage.

Lube purists are averse to lubes with PG because of misinterpreted studies, confusion with compounds with similar names (PPG and EG), and published MSDS sheets that indicate it could trigger an immune response resulting in inflammation, discomfort, intestinal distress, and potentially anaphylactic (full body) allergic reactions. PG and all other lubricant bases can trigger similar allergic responses.

It is rare to find a lubricant with only PG, so attention must be paid to other ingredients to determine toy and gear compatibility. Obstetrical lubricants that contain only PG and CMC are safe for all toys and all gear.

Compared to PEO, PG is easier to cleanup. It washes with soap and water and a little bit of scrubbing. It is not known to stain furniture, clothing, or bedding; however, it is often coupled with lipids, petroleum distillates, and silicone which may stain or leave indelible marks.

Environmentally, PG degrades easily and does not linger in streams, rivers, lakes, and oceans. It is harmless to aquatic life. The data on PPG is less clear.

Most lubes with propylene glycol have parabens or other preservatives that extend shelf life for long periods of time. Even lube used in the play area does not typically need to be discarded immediately after a session ends.

Follow any expiration dates on lube packaging. Propylene glycol is stable for at least two years when stored at ambient temperatures in closed containers and away from sunlight and other sources of UV light. Discard remaining lube after two years as it will have degraded and lost lubricity.

Pure PG can be poured down the drain to be processed by sewage systems.

Recycle empty containers.