‘PEG 8’ and Other Mysteries at the Drugstore

Week after week, you plop them in the grocery cart. Shampoo, deodorant, toothpaste.

Besides their common goal of keeping you healthy and presentable, the products share another feature. Each contains multisyllabic, tongue-twisting ingredients, listed in teensy print that goes unnoticed until you’re stuck in a mile-long checkout line or you get a rash.

What are all these ingredients and what do they do? Here’s a sampling of some of the most common.

Shampoo

* Sodium laureth sulfate.

A cleanser derived from coconut and palm kernel oil, it’s mild yet efficient, says a spokeswoman for John Paul Mitchell Systems, maker of hair care products.

“It’s a good foaming agent and it doesn’t strip oils [from the hair] too much,” adds James Parr of Advanced Research Laboratories, which manufactures Citre Shine and Thicker Fuller Hair products.

* Water.

“Shampoo is typically 75% to 95% water,” Parr says. “You need water because, otherwise, the ingredients would be too concentrated. They would over-clean the hair.”

* Glycol stearate.

A fat derived from stearic acid, it acts as a product thickening agent--or what’s known in the biz as a pearlizing agent. Turn a see-through bottle of shampoo upside down. If a glob-like “pearl” forms and rises, it’s a good bet that the shampoo contains glycol stearate.

* Disodium EDTA or tetrasodium EDTA.

Both are chelating agents, designed to prevent bacterial growth in the product. Typically, shampoo shelf life is a year to 15 months. The more natural the ingredients, the shorter the shelf life. The more preservatives, the longer the shelf life. (“Fragrances and herbal essences break down first,” Parr says. “So if you buy a shampoo and it doesn’t smell quite right, that shampoo might be quite old.”)

Deodorant

* Aluminum zirconium tetrachlorohydrex gly.

Simply put, this active ingredient, common in deodorants and antiperspirants, is an aluminum salt that helps prevent wetness and odor, says Eric Kraus, spokesman for the Gillette Co., which manufactures deodorants and antiperspirants.

* Fragrance.

Just hope this cover-up effect kicks in should the aluminum zirconium blah-blah-blah fails.

* Quaternium-18 hectorite.

A clay substance, this is a kind of suspending agent that keeps the mixture consistent.

Toothpaste

* Stannous fluoride, sodium fluoride or sodium monofluorophosphate.

Toothpaste contains one of these, which is the active ingredient that helps prevent cavity formation, says Bob Tricca, a chemist for Oral-B Laboratories in Belmont, Calif.

* Sodium lauryl sulfate.

Similar to sodium laureth sulfate in shampoo, it works as a foaming, cleansing agent. “Most folks like a fair amount of foaming when they’re brushing their teeth,” says Diane Rooney of Oral-B. “It’s kind of a signal [to them that] it’s doing something.”

* Calcium pyrophosphate.

“It’s an abrasive in charge of stain control,” Tricca says. It’s what helps keep the coffee from sticking to your pearly whites.

* Silica.

Another abrasive, similar to calcium pyrophosphate.

* PEG 8.

This ingredient helps give a toothpaste squeezeability. It stands for polyethylene glycol (8 is the molecular weight).

* Xanthan gum.

This helps hold toothpaste together.

* Doheny cannot answer mail personally but will attempt to respond in this column to questions of general interest. Please do not telephone. Write to Pharm Report, Life & Style, Los Angeles Times, Times Mirror Square, Los Angeles, CA 90053.