Lube ingredients to avoid, and why each one is on the list.

The lube ingredients to avoid are glycerin and propylene glycol in high amounts (they drive osmolality), parabens, fragrance and flavor, warming and cooling agents, nonoxynol-9, chlorhexidine, polyquaternium 15 and petroleum. None is poison. Each either dries tissue, irritates it, or breaks condoms. A short ingredient list, read against the WHO thresholds, avoids all of them.

Glycerin and propylene glycol, the osmolality drivers.

These two are on the list for one reason: concentration. Glycerin (glycerol) and propylene glycol are humectants added to make a lube feel slick and keep it from drying. They also dissolve into the water and push osmolality up. Vaginal tissue sits around 260 to 290 mOsm/kg. A lube loaded with glycerin can measure 2,000 to 8,000, and at those levels it pulls water out of the cells it touches. That is the sting, the drying out an hour later and, in lab studies, the stripping of the top tissue layer.

The WHO advisory is specific. To keep a lubricant under its 1,200 mOsm/kg ceiling, glycerol should stay under 9.9 percent of the formula and propylene glycol under 8.3 percent. The ideal is 380 or under, which in practice means little or no glycerin at all. K-Y Jelly, which contains glycerin, measures 2,007 to 2,510. The original Astroglide Liquid measures 6,113 to 8,064.

A small amount of either is not a problem. The number is. Look the product up in the lube index rather than scanning the label for the word.

Parabens.

Methylparaben, propylparaben and their relatives are preservatives. They keep water based products from growing mold. In laboratory studies they show weak estrogen like activity, which is why they became a target, and regulators still consider them safe at the levels used in cosmetics. We list them here for a practical reason. Every good lube on our index dropped them years ago, so there is no trade off in avoiding them, and some people do react to them.

Fragrance and flavor.

Scent and flavor are the most common contact allergens in cosmetics, and the vulva and vagina are more reactive than the skin on your arm. A flavored lube is designed for the mouth, not for penetration. If you use one, wipe it off before switching. Unscented is the default for anything that goes inside.

Warming and cooling agents.

Warming lubes get their heat from high levels of glycol or similar, and cooling lubes from menthol or peppermint. Both are irritants by design. The sensation is the tissue reacting. FDA filings for warming products routinely show osmolality far above the WHO ideal, because the same ingredient that warms is the one that drives the number. The plain version of the same brand is almost always the better product.

Nonoxynol-9.

Nonoxynol-9 is a spermicide that was added to some lubes and condoms for decades. The WHO advisory says lubricants containing it should not be used. Studies found it damages the epithelium and, rather than protecting against HIV, increased the risk of transmission in frequent users. It is rare in lube now, but older products and some spermicidal gels still carry it. Read the label.

Chlorhexidine and polyquaternium 15.

Two more the WHO names. Chlorhexidine gluconate is an antiseptic preservative. In laboratory work it was hard on vaginal tissue and on the lactobacilli that keep the vagina acidic. Polyquaternium 15 is a conditioning polymer that, in laboratory studies, increased HIV replication rather than reducing it. Neither appears in the lubes we recommend. Both appear in products that are still on shelves, so they are worth a glance at the fine print.

Petroleum and mineral oil.

Petroleum jelly, mineral oil and baby oil are on the list for two reasons. Oil destroys latex and polyisoprene condoms within minutes. And petroleum products linger inside the body far longer than water based lube, which some clinicians link to irritation and infection. Food grade plant oils are a better version of the same idea. Petroleum is the one most clinicians say to skip outright. See can you use Vaseline as lube.

How to read a label.

Ingredient	Why it is on the list	Where it shows up
Glycerin	Drives osmolality, blamed for yeast flares	Most drugstore water based lubes
Propylene glycol	Drives osmolality, warming effect	Warming lubes, many gels
Parabens	Preservative, weak hormone like activity in lab studies	Older formulas
Fragrance, flavor	Common allergens	Flavored and scented lubes
Menthol, high glycol	Irritant by design	Warming and cooling lubes
Nonoxynol-9	Damages epithelium, WHO says avoid	Spermicidal lubes and condoms
Chlorhexidine gluconate	Harms tissue and lactobacilli in lab studies	Some preserved gels
Polyquaternium 15	Increased HIV replication in lab studies	Some conditioning formulas
Petroleum jelly, mineral oil	Breaks latex, lingers	Vaseline, baby oil

The short version: a lube with five or six ingredients you can pronounce, no glycerin, no scent, and a published osmolality under 380 is the goal. The label can tell you the first three. Only the data tells you the last one.

Two lubes that avoid all of it.

Good Clean Love Almost Naked (240 to 269 mOsm/kg, pH 4.7) and Sliquid Organics Natural (106 mOsm/kg, pH 4.0 to 4.4) are aloe based, glycerin free, paraben free, fragrance free, and were the two products in the Dezzutti study that caused no measurable damage to tissue. Either is a safe default.

If you have switched to a clean, low osmolality lube and still get burning, pain, bleeding or recurring infections, see a clinician. The lube may never have been the cause.