It seems to me that the health risks of hand washing after urinating are greatly exaggerated in the world. I understand that hand washing after defecation is an entirely different story as fecal matter contains very harmful microbes.

If it is dangerous, I'm wondering why so few people contract disease from performing oral sex on unwashed genitalia? It would seem to me that the unwashed genital would be harboring far more bacteria than the hand that touched it.

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    It's not just touching genitals. It's also about being in a place where there is lots of urine splashing around in the air. Feb 2, 2015 at 17:13
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    @DJClayworth: But urine (from a healthy animal) is sterile, and thus minimally harmful.
    – Flimzy
    Feb 2, 2015 at 17:22
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    I am given to understand that urine is sterile, but the surface of the genitals is not. That said, I am at work and cannot put much time into researching this at the moment. Feb 2, 2015 at 19:31
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    @Scottie: Uh, your question isn't really about the health risks of oral sex at all. I didn't vote to mark it as duplicate because this question is limited to urination, where the other question is all bathroom visits.
    – Oddthinking
    Feb 2, 2015 at 21:48
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    You cannot compare two things totally different.One is to use toilet and holding your p... and go without washing your hands with soap and another thing is to receive oral sex which is very dangerous for both people, who receive and who is offering. If you think how many caries you can have in your tooth and how is smelling in the morning when you wake up, think again if you 100% safe after you received oral sex. Orrr,if a woman is offering you oral sex, think how many p.....was I her mouth before you. Don"t take it like offence but this is true, both ways you can take viruses and get sick, if
    – Isabella
    Feb 4, 2015 at 23:07

2 Answers 2



From the abstract (highlighting is mine):

Harmful microorganisms can be transferred to hands from contaminated surfaces people come into contact in daily life. Contaminated hands can transmit disease to one self as well as to others. A study was done to determine the extent to which hand hygiene practices and toilet door knobs contribute to the bacterial load of hands of toilet users in a medical school. Swabs were taken from a randomly selected sample of 60 medical students for bacterial count from both hands before and after toilet use and from door knobs of six toilets. Only 40 (66.7%) claimed they washed hands with soap. Significantly more females (83%) used soap to wash hands compared to males (50%). Bacterial load in the hands of both males and females showed an increase after toilet use. The increase was significant among male students. The dominant hand had a significantly higher bacterial load than the other. The mean bacterial load of male toilet door knobs (12 CFU/cm2) were significantly higher than of female toilet door knobs (2.5 CFU/cm2) (𝑃 < 0.0 5). Staphylococcus aureus was isolated from the hands of 21 students. Toilets and washrooms should be designed so as to eliminate the sources of contamination of the hands.

There are differences between circumcised and uncircumcised men regarding the bacteria found on and inside the urinary tract:

Circumcision was associated with a significant change in the overall microbiota (PerMANOVA p = 0.007) and with a significant decrease in putative anaerobic bacterial families (Wilcoxon Signed-Rank test p = 0.014). Specifically, two families—Clostridiales Family XI (p = 0.006) and Prevotellaceae (p = 0.006)—were uniquely abundant before circumcision. Within these families we identified a number of anaerobic genera previously associated with bacterial vaginosis including: Anaerococcus spp., Finegoldia spp., Peptoniphilus spp., and Prevotella spp.

I'm honestly not certain whether any of those fall under the heading of "harmful bacteria". The paper is focusing more on aspects of a health penile microbiome and its effects on HIV transmission.

The CDC have their own things to say:

Feces (poop) from people or animals is an important source of germs like Salmonella, E. coli O157, and norovirus that cause diarrhea, and it can spread some respiratory infections like adenovirus and hand-foot-mouth disease.

But it looks like they focus on transmission through fecal bacteria.

Cecil Adams, of Straight Dope fame, did do a column on this subject, including discussing cunnilingus and fellatio:

What you may not know is that washing will not make the coliform bacteria go away. They're holed up in the pores of your skin and nothing short of sandblasting — certainly not your morning shower — is going to get them out. Showering merely gets rid of the ones that have strayed onto the surface. The bacteria won't do much harm if they stay put, but when you urinate your fingers come in contact with Mister P. long enough for the coliform bacteria in your pores to hop aboard. Your fingers subsequently touch lots of other infectible items. If you don't wash your hands with soap and water (soap gets rid of the skin oil that the bacteria stick to) … hello, Typhoid Mary.


... the truth is you can catch lots of bugs via oral sex. Many of them are transmitted by, or have their transmission facilitated by, coliform or other fecal bacteria or, for that matter, fecal viruses. There's no point in stopping now though. You can catch most of the same germs from intercourse, kissing, or simply holding hands.

Leaving aside that The Straight Dope is entertainment material, and often somewhat inaccurate, take it with a grain of salt, but it fits with what the other sources say, that it's fecal bacteria, that it's all over your genitals, and casual rinsing isn't going to make it go away. Oral sex isn't really adding that much largely because, well, most of us are pretty smeared in fecal bacteria as it is.

I honestly was surprised to find so little actual evidence that hand-washing helped. I knew that anti-bacterial soap has been shown to be no better than regular soap, and that hot water only helps in terms of reducing the amount of soap film on your hands, but I really did expect handwashing to have a higher impact on health in this case. Still extremely useful for surgery, less useful after the bathroom.

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    If you wash your hands and then touch the door knob, which seems to be the worst part, how important was washing your hands? On the other hand, if there are toilets designed so that you do not touch anything (automatic doors ...), is there any need to wash your hands? Those questions seem unaddressed to me.
    – Suma
    Feb 2, 2015 at 19:23
  • There are toilets where it is designed that you do not touch the door ranging from automatic doors to ones with a toe-catch so you can pull it out with your foot. And some toilet guidelines recommend using a paper towel as a barrier with the door handle. But I feel like you're moving the goalposts by basically saying "But if you're going to get dirty again..." :) Feb 2, 2015 at 19:33
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    @Suma, I've heard arguments that state frequent hand washing throughout the day is a good practice, and that bathroom breaks are simply a good time to do it. There is most definitely a coloration to when hand washing became mainstream and the number of illness related deaths in the late 19th century. What I'm not sure of, is the correlation tied to hand washing after using the bathroom specifically, or did frequent hand washing show a drop in disease, and it was falsely attributed to washing after going to the bathroom?
    – Scottie
    Feb 2, 2015 at 20:22
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    I've often wondered if I'm negating the benefit of washing my hands when I use the (bacteria laden?) door knob to leave the bathroom - we have "green" high powered hand driers and no paper towels to use to open the door (and I'm not sure what I'd do with it after I opened the door unless the trash can was next to the door)
    – Johnny
    Feb 3, 2015 at 1:49
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    This article speaks only of "toilet use", not specifically urination. I don't believe this answered the question.
    – Scottie
    Feb 3, 2015 at 15:59

This article claims that you should wash your hands, for two reasons: Yes, washing hands works

It's based on interviewing experts, not based on studies:

I took these objections to three experts: Stephen Luby, a researcher with the federal Centers for Disease Control and Prevention; Judy Daly, a Salt Lake City microbiologist and spokeswoman for the American Society for Microbiology; and Susie Craig, a food-safety and hand-washing educator with the Washington State University Extension Service.

Here's what they said on the key issues:

Why should men wash their hands after every restroom use?

"I've heard men say that it's nothing but Victorian prudery" to ask them to wash after urinating, Luby says. "And we cannot show them studies" that prove doing so will protect them or others from illness.

The two reasons given are as follows:

But the experts still recommend washing, for two reasons.

Reason one: You may pick up more germs than you think, from doors, flush handles and other surfaces, and from your own body. "Your gastrointestinal tract is close by," Daly says. "It all fits together, and you can't see where the microorganisms are."

Reason two: The restroom, stocked with sinks, soap and water, is a convenient place to wash off bacteria and viruses your hands accumulate elsewhere during the day. Studies do show groups of people who wash their hands regularly get fewer gastrointestinal and respiratory illnesses.

  • Well, reason 2 is an argumentation which doesn't work, because it would say, if you go for an restaurant, you should wash your hands, independently from using the toilet, because you collected so much bacteria. Feb 3, 2015 at 7:06
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    This appears to be educated anecdotal evidence that suggests that washing hands after urinating is beneficial, but "we don't have any evidence to back it up". Not sure this really answers the question...
    – Scottie
    Feb 3, 2015 at 16:01
  • @Scottie If there are no studies, then I'm not allowed to say, "There are no studies" nor "I found no studies"; but I think I am allowed to (though I haven't found the relevant meta-topic which says so) link to an publication in which an expert says "There are no studies to show".
    – ChrisW
    Feb 3, 2015 at 16:17
  • Fair enough. I read the article and it seems to be conflating general hygienic hand washing as a good practice that helps to reduce the amount of sickness, but it fails to adequately address if urine is an actual cause of disease.
    – Scottie
    Feb 3, 2015 at 16:18
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    @Scottie I suppose it's an indirect answer: "If you didn't wash your hands after urinating then when ever would you wash your hands? Regular (e.g. more than once per day) hand-washing works."
    – ChrisW
    Feb 3, 2015 at 16:22

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