Lube for anal sex: what to look for

Anal lube is important because the anus doesn't lubricate itself. Without lube, the skin inside the rectum can tear, which is painful and can increase the risk of HIV and other STIs, LGBT Foundation says. This guide explains what to look for in a lube for anal sex: the types, which ones are safe with condoms and sex toys, and what the World Health Organization and research studies say about ingredients. It doesn't recommend any brand.

Why do you need lube for anal sex?

Unlike the vagina, the anus isn't self-lubricating, Brook explains, so lots of lube makes anal sex more comfortable for both partners and helps prevent tearing, which can increase the risk of STIs. Brook adds that it is very easy to tear the delicate skin on the anus, and these tears (called fissures) can take a while to heal.

Lube helps condoms too. The WHO says research suggests extra water-based lube is particularly important for anal sex. In one study of gay men that it cites, condoms broke 3% of the time when the water-based lube supplied with them was used, compared with 21.4% when no extra lube was used.

Spit isn't a good substitute. The Terrence Higgins Trust says not to use it, because it dries quickly and leaves a condom prone to breaking.

What's the best lube for anal sex?

LGBT Foundation, a UK charity for LGBTQ+ people, says water-based and silicone-based lube are the best for anal sex, and recommends water-based when in doubt. Beyond the type, the WHO's advisory note on lubricants, written in 2012 with the United Nations Population Fund and FHI 360 for organisations that buy lube in bulk for public health programmes, lists what to look for:

• It's compatible with the condoms you use: water-based or silicone-based lube for latex condoms.
• It has a low osmolality, meaning it isn't far more concentrated than the body's own fluids. Ideally that's no more than 380 mOsm/kg, and the WHO set 1,200 as an interim upper limit.
• For anal sex, its pH is about 5.5 to 7, and not above 7.
• It contains no polyquaternium compounds and no spermicide such as nonoxynol-9.

The WHO says the main thing that sets most lubes' osmolality is how much glycol they contain, usually glycerol (glycerin) or propylene glycol. It advised bulk buyers to ask manufacturers for osmolality figures, or for the glycol content if those aren't available.

Types of lube for anal sex compared

	With latex condoms.	Worth knowing.
Water-based	Safe to use	The most widely available type. The WHO said in 2012 that most commercial lubes were highly concentrated (2,000 to 6,000 mOsm/kg), which might damage the lining
Silicone-based	Safe to use	Can damage silicone sex toys, so don't use them together. In a 2012 lab study, the two silicone lubes tested didn't harm bowel tissue samples, though the WHO notes there are no published clinical studies supporting their use as lubes, particularly with latex condoms for anal sex
Oil-based (petroleum jelly, baby oil, coconut oil, butter, lotions)	Don't use: oil can make latex condoms break or tear	Polyurethane condoms can take almost any lubricant with proven safety for human use, but polyisoprene ones are as sensitive to oil as latex
Spit	Not recommended	It dries quickly, leaving a condom prone to breaking (Terrence Higgins Trust)

Sources: the NHS, the World Health Organization (2012), LGBT Foundation, the Terrence Higgins Trust and a 2012 laboratory study. It says on the packet what a condom is made of.

Why does osmolality matter in anal lube?

Lubes that are far more concentrated than the body's own fluids (high osmolality) might damage the lining of the anus, the WHO says. Osmolality is a measure of how concentrated a lube is. The WHO gives the normal osmolality of vaginal fluid as 260 to 290 mOsm/kg and of semen as 250 to 380, and said in 2012 that most commercial lubes were 2,000 to 6,000.

The WHO says several papers suggest high osmolality might damage the lining of the vagina and anus. It adds that the damage could in turn increase the risk of HIV and other STIs, particularly when condoms aren't used every time, and that the effect might be more important when these lubes are used in the rectum. The research behind that:

• In a 2007 study at Johns Hopkins University, 10 volunteers each had two gels placed in the rectum. The highly concentrated one (3,429 mOsm/kg) stripped away more of the lining 10 cm from the anus than one matched to the body's fluids (283 mOsm/kg).
• A 2012 laboratory study tested 14 over-the-counter lubes. The highly concentrated water-based ones reduced the health of tissue samples and damaged their surface layer, while two nearly iso-osmolar water-based lubes and both silicone-based lubes showed no significant changes.
• A 2011 laboratory study of 41 lubes found most were hyperosmolar, and the barrier reading of a layer of gut cells grown in the lab dropped by about 60% two hours after exposure to every lube tested.
• A 2012 study of 380 people in Baltimore and Los Angeles who had receptive anal sex found that those who had used lube every time in the past month were more likely to test positive for an STI (9.5%, against 2.9% of those who hadn't used it every time). The authors said the findings suggest some lube products may increase vulnerability to STIs, and that further research is essential to clarify if lube use poses a public health risk.

None of this makes going without lube safer: without it the lining can tear (LGBT Foundation), and the WHO says research suggests extra water-based lube is particularly important for anal sex. For bulk buyers, its advice is to choose lubes that are less concentrated.

Does pH matter for anal and vaginal lube?

Yes. The healthy vagina normally has a pH of 3.8 to 4.5, while the rectum is closer to neutral (pH 7), the WHO says. So the ideal lube for vaginal sex has a pH of about 4.5, and for anal sex about 5.5 to 7, and no single lube can meet both. A high pH in the vagina can increase the risk of bacterial vaginosis, the WHO adds.

Which ingredients should you avoid in anal lube?

The WHO advises avoiding polyquaternium compounds and spermicides such as nonoxynol-9, and says preservatives can irritate some people. In more detail:

• Polyquaternium compounds. In the 2011 laboratory study, four lubes significantly increased HIV replication in cells. The WHO notes that polyquaternium is a common ingredient in all four, and says these compounds are best avoided until their role is clearer.
• Spermicide, mainly nonoxynol-9. The WHO says recent research summaries suggest it has significant irritant effects, and that overall its use is not recommended. The Terrence Higgins Trust advises avoiding condoms that contain it.
• Local anaesthetic. The WHO notes that some condoms contain a local anaesthetic, with benzocaine a common example. LGBT Foundation says people can be tempted to use sprays or lube that take away feeling, and points out that if you've lost feeling and don't use enough lube, you may not feel any tears. Our anal sex safety guide explains why pain matters.
• Preservatives. Water-based lubes must contain them, and they can cause irritation and sensitisation in some individuals, the WHO says; parabens are the most commonly used.

Which lubes work with condoms and sex toys?

Water-based and silicone-based lubes are safe with latex condoms and oil-based ones aren't, while silicone lube shouldn't be used with silicone toys. In more detail:

• Latex condoms: use water-based or silicone-based lube, never oil-based (NHS).
• Other condoms: the WHO says almost any lubricant with proven levels of safety for human use can be used with polyurethane condoms, but polyisoprene condoms are just as sensitive to oil-based lubricants as latex, so check what yours is made of first.
• Internal condoms used for anal sex: use lubricant on the outside and inside of the condom (NHS).
• Silicone sex toys: don't use silicone lube with them, because it damages the toy and can make it uncomfortable and unsafe to use (LGBT Foundation). Put a condom on sex toys and change it between partners and between the anus and vagina. Our guide to pegging covers toys and safety in more detail.
• Creams and medicines: don't use latex condoms if you're using antifungal medicine on or around your anus, vulva, vagina or penis (NHS), and some prescribed creams for genital warts can weaken condoms (NHS).

How much lube should you use for anal sex?

LGBT Foundation suggests starting with a few drops and gradually adding more if you don't feel lubricated enough; Brook simply says to use lots. With an external condom, the Terrence Higgins Trust says to apply water-based or silicone-based lube to the condom once it's on, and to make sure no air or lubricant is trapped under the condom when you put it on.

For getting ready before anal sex, including whether to douche, see our guide on how to prepare for anal sex.

When should you get help?

If you're in a lot of pain or discomfort after anal sex, or the bleeding doesn't stop or is a very dark colour, Brook says to seek medical advice. See a GP if anal pain is severe or doesn't improve after a few days, and go to A&E or call 999 if you're bleeding non-stop from your bottom or there's a lot of blood (NHS).

If a condom splits or comes off, get urgent help from a pharmacist, a sexual health clinic, NHS 111 or a GP: you may need emergency contraception or an STI test (NHS). For lumps, sores or itching around the anus, see our guide to anal warts and other infections around the bottom, or find a sexual health clinic.