Lube can alter vaginal pH. Here’s what to look for on the label

All of us will probably be in need of a lubricant at some point in our sex lives, because our vaginas don’t always get flowing as quickly as our minds do. For some of us, a bottle of lube makes an appearance everytime we have sex, while others use it less often. It can be your best friend when it comes to oral sex (for all sexes) and vaginal sex — especially with semi-impromptu quickies — but absolutely for anal sex, because the anal passage doesn’t self-lubricate.

Postmenopausal women are more likely to experience vaginal dryness — which stems from a drop in oestrogen levels — so might be reaching for the lube more often, but women of any age can experience it, too. Lube can make sex more playful, heighten sensations, and reduce soreness, possibly meaning you can go at it for longer.

But not all lubes are created equal. Lube can contain ingredients that are irritating to the vagina, cause an imbalance in pH levels, or actually promote dryness.

But how do you separate the vagina-friendly from the vagina-harmful? Check the label. Here’s what you want to see and what you don’t.

A CE certification is essential

If a product is CE marked, it’s a confirmation that it’s safe for the bodily environment it was intended for, by European Economic Area (EEA) standards. Without this, there’s no confirmation that your lube product doesn’t contain anything that’s grossly offensive to your vulva skin and vaginal pH. Although all products with CE certification are considered safe, chemist, ex-Pharma consultant, and co-founder of an organic lube company, Sarah Brooks says that while a CE mark indicates that a lubricant is safe, it’s better to go for lubes that have further certifications, too.

“I would suggest only buying lubes that have a CE mark followed by a four number code — these are classed as grade two medical devices and have been thoroughly tested and approved for actual use within the vagina”

“All CE marked lubes are technically safe, classed as grade one medical devices,” she says. “If a product isn’t CE marked or doesn’t list its ingredients — you can’t possibly know if it contains allergens or anything that will irritate you.

“I would suggest only buying lubes that have a CE mark followed by a four number code — these are classed as grade two medical devices and have been thoroughly tested and approved for actual use within the vagina. It’s also confirms that the product has been properly preserved.”

A four digit identification number alongside a CE mark signals to consumers that a Notified Body — a specialist organisation appointed by an EU member state — was involved in the safety assessment process for a product.

Glycerin and friends

When it comes to individual ingredients that cause vaginal pH imbalances and aggravate the skin of the vulva and the walls of the vagina, glycerin is the patron saint of irritants. Glycerin — also known as glycerol or glycerine — is a sugar alcohol polyol compound. While glycerin can act as food for some types of healthy vaginal flora, it can also act as food for yeast strains, most notably candida albicans.

Lubricants containing any form of glycerin or sugar alcohol have the potential to cause or encourage vaginal thrush, because candida — the yeast that commonly causes thrush — can use sugar to spur development into an infection.¹ Look out for long, and often complicated names on lube labels that contain any version of the word “glycol” or “glycerin” — these are normally some sort of derivative of a sugar alcohol, and it’s safer to avoid ingredients like this altogether.

“At very low concentrations, glycerin can act as food for candida albicans,” says Sarah. “If a lubricant contains more than 20% glycerin, it’s likely to also cause mucosal irritation, where water moves out of the cells in your vaginal walls to a semi-permeable membrane to equalise pressure by the process of osmosis.

“Glycerin can pull water out of mucous membranes, and if a lubricant contains concentrations of more than 40% glycerin, it will actually start to break down your mucous membranes.”

Once the mucous membranes of your vaginal and vulva tissues become irritated or start to break down, this can cause vaginal dryness. The sensitivity and irritation of these tissues will also make you more susceptible to STIs, and make vaginal wall tears more likely.²

“The skin on the rest of our bodies has this protective last layer, while the skin of the vagina and vulva — like the skin on the inside of our cheeks — doesn’t. This makes them more fragile tissues”

Glycerin and its other forms are commonly used in many moisturising products. Interestingly, they actually act as a great skin hydrating compound by drawing water into the skin. The opposite happens with the more delicate skin of the vulva and vagina because it doesn’t have an additional protective layer of keratinized cells, which is the outermost layer of skin that’s effectively dead and full of keratin — a protein — that makes our skin waterproof.

“This is known as the stratum corneum,” says Sarah. “The skin on the rest of our bodies has this protective last layer, while the skin of the vagina and vulva — like the skin on the inside of our cheeks — doesn’t. This makes them more fragile tissues.”

pH, spermicide and infection

Sarah points out that not all lubes state their pH level on the label. A healthy vaginal pH level is between 3.8 and 4.5, which is fairly acidic, keeping harmful bacteria at bay and encouraging healthy bacteria. You should try to only choose lubricants that state a pH level of around four on the label.

“Yeast growth and consequent thrush outbreaks start to happen at about a pH level of five,” says Sarah. “If the vaginal pH level reaches a six or seven, the entire bacterial balance of the vagina becomes compromised and infections like bacterial vaginosis become very likely.

“Using a lubricant that is pH matched to the vagina is critical so you’re not encouraging any infections.”

GP Dr Shahzadi Harper highlights that postmenopausal women are naturally more likely to have a vaginal pH level that’s higher than 4.5. This is because of lowered oestrogen levels following menopause.³

“Vaginal hormonal changes because of menopause also affect the protective barriers of the vulva and vagina skin,” she says. “A drop in oestrogen can cause the vulva skin to become crepe-y, and make dermatitis conditions in that area more likely.”

Silicone and water-based lubricants are less likely to cause irritation of the vagina and vulva areas for postmenopausal women, compared to oil-based lubricants. Silicone lubricant is longer lasting than water-based lube, and offers the greatest amount of lubrication.

Nonoxynol-9 is the active ingredient used in most spermicide lubricants. It has been found to be damaging to vaginal tissue, making severe irritation and cuts highly likely, and consequently greatly increasing the risk of STI transmission

Some lubricants also contain spermicide, which immobilize sperm so that it can’t fertilise an egg. They are notorious for causing irritation of the vaginal tissue.

Nonoxynol-9 (N-9) is the active ingredient used in most spermicide lubricants. It has been found to be damaging to vaginal tissue, making severe irritation and cuts highly likely, and consequently greatly increasing the risk of STI transmission. A 2002 study of 765 women concluded that multiple use of N-9 could cause toxic effects enhancing HIV-1 infection.⁴ A second study found that nonoxynol-9 may increase HPV’s “ability to infect and persist”.⁵

What about anal lubricants? The anus has a higher optimal pH level than the vagina that’s more alkaline, at around seven. Using lubricant that’s specifically made for the vagina — with a pH level of four — in or around the anus could be irritating for anal skin.

“Matching your lubricant’s pH to your anal pH for anal sex is still important,” says Sarah. “Anal tissue is still delicate and needs the right pH balanced lubricant to be protected too, you don’t want to do any damage and make STI and HIV tranmission easier.”

Flavourings and fragrances

Fruity, floral scents, and flavours added to lubricants are not only likely to irritate the vaginal environment and upset its pH balance — they also play into harmful untruths and stigma to do with female genitals.

Vaginas are meant to smell and taste like vaginas. They are not meant to smell or taste like fruit, candy, flowers, or Pepsi Cola (sorry, Lana). Trying to make them taste and smell this way can ironically actually make them taste and smell “worse”. Once the pH of your vagina becomes imbalanced, you become more susceptible to infections like BV, which causes a strong, fishy, and unpleasant odour.⁶

A healthy, pH-balanced vagina is more likely to have a slightly metallic taste, indicating its acidity

A healthy, pH-balanced vagina is more likely to have a slightly metallic taste, indicating its acidity. To make a lubricant taste like anything sweet, a form of sugar — like glycol — might need to be added, which yeast likes to feast on. Someone’s natural vaginal odour can change throughout their cycle, becoming stronger just before their period, because blood raises pH levels, and this is normal.

“Fragrances and flavourings can absolutely cause irritation,” says Sarah. “If any form of sugar is used, there’s a potential for thrush, and if essential oils have been used, they are likely to cause irritation too.

“If the labelling only says ‘fragrance’, they are not being specific about what’s been used. Don’t assume it won’t be irritating for the vagina and vulva area.”

Certified organic options

Many producers of lubricants claim their products are “organic”. A product that has been tested and verified as organic will have a certified organic logo from a known organisation, like the Soil Association. This guarantees that all ingredients used are actually organic, and in the case of lubricants, most likely plant-based.

A certified organic lubricant will also be free of parabens, which have been associated with the development of breast cancer by some studies, though a definitive link between the two hasn’t been proven.⁷

“Parabens behave like oestrogen in the body, so they could possibly interfere with hormone treatment post cancer”

“For women recovering from any oestrogen positive cancer, using a lubricant that contains parabens is not advisable,” says Sarah. “Parabens behave like oestrogen in the body, so they could possibly interfere with hormone treatment post cancer, or just raise oestrogen levels in the body, which you absolutely don’t want if you’ve had an oestrogen-positive tumour before.”

Sarah stresses that all certified organic lubricants will be biodegradable, which makes them less likely to linger inside the vagina or body, and less damaging to the environment short term and long term.

Oil, silicone, or water based?

While some experts say the choice between oil, silicone, and water based lubricants is a matter of personal preference — unless you are using silicone toys, in which case, silicone lube will slowly disintegrate these toys, or latex condoms, which oil-based lubes affect the integrity of — Dr Harper says that water-based lubricants are the ideal choice for vaginal sex, because oil-based lubes have the potential to mess with pH levels and possibly encourage thrush or BV. Water-based lubricant most closely mimics the vagina’s natural lubrication.

“Oil-based lubricants don’t exactly have an alkaline pH,” she says. “But they can sometimes slightly raise vagina pH levels, which can disrupt vaginal flora. Silicone-based lube’s ability to break down silicone toys, and oil-based lube’s ability to break down condoms makes water based lube a safer option that’s less likely to cause irritation and other issues.”

The header image features two tubes of lube against a background of gushing water, indicating pleasure, arousal and lubrication

Page last updated July 2019