This article originally appeared in HIV Treatment Update, a newsletter published by NAM between 1992 and 2013.

The ‘lubes’ used most often in sex may actually make HIV transmission more likely. Gus Cairns explores some unnerving new findings from the 2010 International Microbicides Conference.

Do lubricants protect?

It’s a mantra of ‘safer sex’: always use a condom and water-based lube. The lube makes sex more comfortable and it needs to be water-based because oily lubricants damage condoms.

But this may have also conveyed an idea that lubricants might contribute a bit to sexual safety in themselves, minimising trauma and bleeding, and offering a degree of protection in sex without a condom.

There’s never been any data to prove this, and the evidence from one placebo-controlled microbicide study suggests that using lube is no better than ‘dry’ sex. The HPTN035 study was the smaller of two efficacy trials of the microbicide PRO2000 but – uniquely for a microbicide trial – it included two control arms: 1000 women got PRO2000, 1000 got the placebo gel, and another 1000 got no gel at all.1

Glossary rectum The last part of the large intestine just above the anus. microbicide A product (such as a gel or cream) that is being tested in HIV prevention research. It could be applied topically to genital surfaces to prevent or reduce the transmission of HIV during sexual intercourse. Microbicides might also take other forms, including films, suppositories, and slow-releasing sponges or vaginal rings. placebo A pill or liquid which looks and tastes exactly like a real drug, but contains no active substance. safer sex Sex in which the risk of HIV and STI transmission is reduced or is minimal. Describing this as ‘safer’ rather than ‘safe’ sex reflects the fact that some safer sex practices do not completely eliminate transmission risks. In the past, ‘safer sex’ primarily referred to the use of condoms during penetrative sex, as well as being sexual in non-penetrative ways. Modern definitions should also include the use of PrEP and the HIV-positive partner having an undetectable viral load. However, some people do continue to use the term as a synonym for condom use. relative risk Comparing one group with another, expresses differences in the risk of something happening. For example, in comparison with group A, people in group B have a relative risk of 3 of being ill (they are three times as likely to get ill). A relative risk above 1 means the risk is higher in the group of interest; a relative risk below 1 means the risk is lower.

This trial reported a nearly statistically significant 30% efficacy for PRO2000, which got prevention advocates very excited until their hopes were dashed by the subsequent, larger, MDP301 trial. However, what was just as interesting was that the researchers found absolutely no difference in the rate of infection by HIV or sexually transmitted infections (STIs) between women who used the placebo gel (hydroxyethylcellulose, or HEC) when they had sex, and ones who didn’t use gel.

So no protection there, but no harm.

Are lubricants dangerous?

Two other presentations at the recent Microbicides Conference, however, produced much more unsettling news: while HEC might not have any influence on HIV infection, commonly used lubricants might do, and negatively so - actually facilitating STI - and possibly HIV - infection.

Pamina Gorbach from the University of California, Los Angeles, studied 302 US men and women who had had receptive anal intercourse (RAI). Her study is part of the U19 programme, which aims to develop a rectal microbicide.2

There are more straight women than gay men who have anal sex, simply because there are more of them, but gay men tend to have it more often. So Gorbach weighted her sample by recruiting women who’d had RAI in the last year but men who’d had it in the last month.

The group was 58% male, half African-American and the average socioeconomic status was poor: 21% of the group classed themselves as homeless and 35% as disabled.

Three-quarters of the group had used a lubricant the last time they had RAI. Lubricant use was less common in African-Americans (38.5%) and Hispanic people (58%). More HIV-positive people used a lubricant than HIV-negative people. Two-thirds had used a water-based one such as KY Jelly, between a quarter and a third had used a silicone-based lubricant and one in six an oil-based lubricant.

More than two-thirds (68%) of people diagnosed with rectal gonorrhoea and/or chlamydia had used a lube compared with a third of people who had not, and over one in nine (11.7%) of lubricant users were positive for these rectal STIs compared with one in 22 (4.5%) who did not use lubricant..

So people who’d used a sexual lubricant for RAI were more than three times more likely to test positive for a rectal STI than non-lube users. These findings were statistically significant.

Was it because lube-users had more sex? No. Less likely to use condoms? No. Did they have more partners or more who were HIV-positive? No and no. Using a lubricant was an independent predictor of having an STI. It increased the risk in its own right.

HIV infections weren’t measured so there’s no direct evidence on whether lube might make you more vulnerable to HIV. But rectal gonorrhoea is used as the most accurate ‘surrogate marker’ for who’s vulnerable to HIV in a community. An increased risk of gonorrhoea may imply an increased risk of HIV.

Which lubes are safe?

So what’s going on? Gorbach’s own study was too small to divide up the relative risk of different types of lube, but the suggestive findings of a test-tube study by the University of Pittsburgh suggested a mechanism.

Presenter Charlene Dezzutti and her colleagues tested for toxicity six lubricants that can be bought over the counter in the USA.3 These were five water-based lubricants (Astroglide, Elbow Grease, ID Glide, KY Jelly and PRÉ vaginal lubricant) and one silicone-based one (Wet Platinum). They tested the lubes on explants: sections of rectal lining kept alive in nutrient baths.

Four of the water-based lubricants completely stripped off the epithelium (outer layer) of cells from rectal tissue. In contrast, PRÉ and Wet Platinum caused relatively little damage. Astroglide caused almost as much damage as nonoxynol-9, the spermicide that has already been shown to double the risk of HIV infection.

The difference between PRÉ and the other four water-based lubes was that the other four were hyperosmolar or hypertonic. What this means is that they contained more dissolved salts and sugars than the fluid inside the body’s own cells. When this is introduced into the rectum (or similar body cavity), it causes water to diffuse out of the cells lining the rectum into the rectum itself. The cells become leaky and can disintegrate altogether. PRÉ, on the other hand, was isotonic: its composition mimicked the body’s own fluids, as does HEC.

The problem is that PRÉ has been marketed as a specialist sperm-safe vaginal lubricant for women trying to conceive, whereas the other four water-based lubes are primarily marketed to gay men as those condom-friendly lubes you should use in safer sex.

The one silicone lube tested is also aimed at gay men, and seems safe – but silicone lubes are expensive.

What should we tell the community?

“What’s our take home message here?” Gorbach was asked. The long-term message is clear: there is an urgent need to conduct further research into sexual lubricants, and probably introduce more stringent safety checks for them before licensing them for over-the-counter sale.

But what short-term message to give is much more problematic.

Gorbach said that people should choose their lubricating substance carefully; but her study itself did not rate different lubes for safety and Dezzutti’s one was a lab study that only evaluated a handful, not all for sale in the UK (“And,” she commented to aidsmap, “Wet Platinum and PRÉ are very runny, not appealing to most people”).

How are people to know which lubes are safe? Where does it leave all those condom-distribution schemes that hand out sachets of water-based, hypertonic lube? Should we avoid lubes altogether?

A study by the International Rectal Microbicides Advocacy (IRMA) in 2008 suggests not.4 Jim Pickett, its Chair, emphasises that condoms make the biggest difference: condoms-plus-lube are safer than no-condom-no-lube.

“But for the people who don't use condoms consistently, or ever during anal sex,” he adds, “I would still recommend using lube, lots of it. The damage done during dry anal sex likely trumps any damage [from] lube.”

Pamina Gorbach, however, warns: “There is no actual data showing that it is damage to the rectum during dry sex that facilitates HIV transmission. The high rates of HIV transmission during anal sex in general suggest that there is another mechanism.

“So yes, encourage lube use because it facilitates and encourages condom use. But just don’t say it is actually harm reduction – we don’t have any data to support that. I wish we did!”

Common sense would suggest that people aren’t going to stop using lubricants.

“Until we know more, I certainly don’t think we should discuss stopping the use of lube with anal sex, and people wouldn’t enjoy it, anyway,” says Marc-André LeBlanc, Secretary of IRMA. “I don’t think we can come to any grand conclusions about which lubes are safer without more research; for now, I think avoidance of trauma is still your best bet.”

Forking out more for silicone or isotonic lubes is probably not a bad idea and is unlikely to increase your risk compared with the more familiar water-based ones. If you can’t afford those, there is always that freely available isotonic fluid, spit. Maybe we should market little sachets of it.