The results of two research studies were released in 2010 (at the International Microbicides Conference) which, some may think, call into question the safety of using lubricants for anal sex. But what do these results show? Is the evidence enough to change our safer sex messaging? We don't think so -- have a look at the rationale for why we don't think our messaging about lube use for anal sex should change.
For one of the studies, researchers analyzed different lubricants (lubes) in a lab. They found that many of the lubes had higher amounts of dissolved salts and sugars than normally found in a cell. Because of this, some of the lubes had a toxic effect on the anal tissue studied in a test tube in the lab. This caused anal tissues to be stripped away.1If these products have the same effect when used in people, the damaged anal tissue could be more vulnerable to HIV and other sexually transmitted infections (STIs) than it already is.
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The researchers tested six lubes that can be bought over-the-counter. Five were water-based lubes (Astroglide, Elbow Grease, ID Glide, KY Jelly and Pré vaginal lubricant) and one was silicone-based (Wet Platinum).
The physical properties of the lubes were measured and four (Astroglide, Elbow Grease, ID Glide and KY Jelly) were found to draw water out of the cells lining the rectum and into the rectum itself, damaging the cells. When these four lubes were tested on anal tissue in a test tube, they were found to strip away cells in the outer layer of anal tissue. Two of the lubes, Pré and Wet Platinum, caused relatively little damage.
The second study found that women and men who reported using lubes for receptive anal sex in the past were about three times more likely to have a rectal STI when they were tested during the study than those who did not report using a lube. This increased risk for an STI was present even if a condom was used.2
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Between October 2006 and December 2008, 879 men and women from a rectal microbicide research initiative were surveyed about their sexual behaviour and were tested for two anal STIs (gonorrhea and chlamydia). Slightly less than half of the study participants (421) reported having receptive anal intercourse in the past year. Of the 229 men and 192 women who had had receptive anal sex, sexual behaviour interviews and anal tests for chlamydia and gonorrhea were available for 302 of these study participants. Within this group, about three-quarters (230) said they had used a lube the last time they had anal sex. Of those, 67% used a water-based lube, 28% used a silicon-based lube, 17% used an oil-based lube (e.g., Crisco), and 6% used numbing lubes. These numbers add up to more than 100% because some people used more than one type of lube.
Anal gonorrhea or chlamydia were found in 5.6% of women and 10.2% of men. About one in nine (11.7%) of the participants who used lube the last time they had anal sex had an anal STI, compared to about one in 22 (4.5%) of the participants who had not used lube. Over two-thirds (68%) of people diagnosed with an anal STI had used a lube compared to one-third (32%) who had not used a lube. When the researchers looked at other factors such as condom use, number of partners, how often someone had sex, their gender, or HIV status, the analysis showed that the use of some lubes for anal sex may increase the risk of getting a rectal STI by about three times.
Definitive conclusions cannot be made based on these studies alone. In the first study, the researchers looked at the effects of lube in a test tube. This does not tell us about the effect of using lube during sexual activity. Even if lubes can damage anal tissue, it may be that their use results in more good than harm. Using a lube during sex makes it less likely that a condom will break or slip off. This alone reduces the risk of HIV or STI transmission. Even when condoms are not used, lube use may reduce trauma to anal tissues, lowering the risk for infection with HIV or another STI. There is no way for us to know from this study whether using lube during anal sex, with or without a condom, will reduce or increase damage to anal tissue or affect the risk for infection with HIV or another STI.
The second study shows a correlation between the use of lubes and the transmission of STIs. However, correlation and causality are two different things: a statistical correlation does not prove a causal relationship. The researchers tried to rule out other causal factors. However, this type of analysis cannot rule out all potential causal factors. For example, people who use lubes may be more likely to transfer STIs between the penis and rectum with their fingers when they apply lube before having anal sex. Furthermore, this study only investigated the relationship between lubes and certain STIs (gonorrhea and chlamydia). This study did not look at HIV transmission so we cannot draw conclusions about the effects of lube on HIV transmission.
There is not sufficient evidence from these two studies to say for sure (a) just how much damage lubes can do to the rectal tissue when used for anal sex and (b) whether lube use can affect the risk of getting HIV or another STI. More research needs to be done to see which lubes are safe, which lubes can damage rectal tissue, if some lubes are more damaging than others, and what the effects of that possible damage on HIV and STI transmission may be.
Certainly, people should not give up using lubes in conjunction with condoms, which provide optimal protection during anal sex.
Safety of lubricants for rectal use: A fact sheet for HIV educators and advocates from International Rectal Microbicide Advocates (IRMA)
Zak Knowles is CATIE's manager of Web content. Before coming to CATIE he worked as an HIV counsellor at Hassle Free Clinic, a sexual health clinic in downtown Toronto. Zak has been living with HIV for 20 years.
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