Keratinization is the process whereby the surface of the glans and remaining mucosa of the circumcised penis become dry, toughened and hard. Normally, the glans is covered by the foreskin, keeping the surface of the glans and inner mucosa moist and supple. After circumcision, however, the glans and surrounding mucosa become permanently externalized, and they are exposed to the air and the constant abrasion of clothing. These areas dry out, causing layers of keratin to build, giving the glans and remaining mucosa a dry, leathery appearance.
Comparison of the glans in an intact penis (above) and a circumcised penis (below)

Source and photo:

From Parenting in America: An Encyclopedia, Volume 1:

When the foreskin is removed, the surface of the glans becomes thickened (keratinized). This adaptation of the glans to environmental exposure provides some protection akin to that of a condom. Debate continues whether keratinization of the glans works to protect the penis against infection more effectively than does the intact foreskin. Even less clear is the effect of the absence of foreskin on sensation. Some reports by men circumcised later in life indicate a significant decrease in perceived sensation to touch over the glans after the procedure, compared with the level of sensation to touch perceived before the procedure.


Effects of Keratinization

Delayed Clinical Presentation — Although the adaptation of glans surface tissue to exposure to the external environment necessarily begins soon after the trauma of circumcision, the process of keratinization progresses for decades and is rarely, if ever, seen as a source of presenting complaints by the OB-GYN or pediatrician who performs the circumcision surgery.

Loss of Glans Sensitivity — However, there are clinical problems due to keratinization that present long after childhood. This is because in protecting the unnaturally exposed glans, keratinization decreases its sensitivity. Research has documented that many different areas of the intact penis are more sensitive than the most sensitive area of the circumcised penis – which is the circumcision scar itself (see Sorrells, M, et al, ‘Fine touch pressure thresholds in the adult penis.’ The full text of this scientific publicatio­n is available: http://www­.nocirc.or­g/touch-te­st/touchte­st.php ). Thus, there is no question that the glans of the circumcised penis is a less sensitive structure than that of the intact penis.

Sex Partner Complaints — Not only has decreased glans sensitivity been associated with complaints of decreased sexual pleasure in men, their partners also suffer consequences of circumcisions. Anecdotal evidence includes complaints of pounding sex, dry unpleasant sex, and vaginal abrasion or lesions that are commonly heard from older women sex partners of circumcised men. The etiology of these complaints involves loss of penis sheath mobility and loss of glans sensitivity in the circumcised penis.

Erectile Dysfunction — Decreased glans sensitivity has also been associated with erectile dysfunction (ED). Men have complained that sexual stimulation during intercourse has been insufficient for them to maintain an erection firm enough for coitus, and have sought relief through the use of prescription medications for treatment of ED.


Reversing keratinization

Different solutions have been suggested, including salicylic acid, circumserum and foreskin restoration.

Early references to keratinization:

"It has been urged as an argument against the universal adoption of circumcision that the removal of the protective covering of the glans tends to dull the sensitivity of that exquisitely sensitive structure and thereby diminishes sexual appetite and the pleasurable effects of coitus. Granted that this be true, my answer is that, whatever may have been the case in days gone by, sensuality in our time needs neither whip nor spur, but would be all the better for a little more judicious use of curb and bearing-rein." E. Harding Freeland, Circumcision as a Preventative of Syphilis and Other Disorders, The Lancet, vol. 2 (29 Dec. 1900): pp.1869-1871.

"I suggest that all male children should be circumcised. This is "against nature", but that is exactly the reason why it should be done. Nature intends that the adolescent male shall copulate as often and as promiscuously as possible, and to that end covers the sensitive glans so that it shall be ever ready to receive stimuli. Civilization, on the contrary, requires chastity, and the glans of the circumcised rapidly assumes a leathery texture less sensitive than skin. Thus the adolescent has his attention drawn to his penis much less often. I am convinced that masturbation is much less common in the circumcised. With these considerations in view it does not seem apt to argue that 'God knows best how to make little boys.'" R.W. Cockshut. Circumcision. British Medical Journal, Vol.2 (1935): p.764.

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  1. Great study, though it focuses only on the undesired effects (cons) of circumcision.

    One big advantage supported by many studies is the fact that the keratinization from circumcision acts almost as a natural condom reducing the risk for HIV infection up to 50%, as the infection normally occurs in de-keratinized areas, like the inner section of lips, anal region, mouth, esophagus, etc. One of the studies made in Uganda, Africa observed two groups of adult sexually active males. 50 were circumcised and 137 were not, all of them were educated on the use of preservatives; after the study finished 30 months later 89% confessed not using condoms during the intercourse. No infections occurred on any of the circumcised men, and 40 of 137 circumcised men became infected.

    Let us be cautious, as this is not proof 100% immunity to the virus, but just how ineffective the HIV virus is to be transmitted through keratinized skin.

    Additional studies have evidence that the transmission rate is reduced by 50% on keratinized circumcised penis.

    1. Thank you for your kind comment and sharing this information.

      The issue with Szabo's study is that it would make sense if we knew for sure that all participants were exposed to the virus, in other words if we knew that all participants happened to have unprotected sex with an HIV+ female, and that no participants contracted the virus through non-sexual paths (transfusions, intravenous drugs, etc).

      Otherwise, there are just too many uncontrolled variables. What happens if some of those men never had any other sexual partner except for their spouse? Or if they used a condom the day that they happened to have sex with a different person. Or that they never ran into an HIV+ partner. Then it's just a number inflating one side of the equation.

      And that's why education is such an important element in HIV prevention, and circumcision is nothing to trust. A male who is faithful and in a monogamous relation with a faithful wife, has no reason to undergo surgery and damage his own sexuality, as his chances of sexual exposure to the virus are minimal, don't you think?

      And a circumcised man who is having unprotected sex with random and frequent partners is simply playing Russian roulette, don't you think?

      This is the same problem that plagued the 3 African RCTs. Furthermore, regarding the 3 RCTs the loss of individuals to the trials was 3 times or more the number of zeroconverted individuals, meaning that if the HIV status of those lost individuals would become known the results of the trial could be completely swayed in one or another direction.

      Referring to circumcision as a "natural condom" is dangerous and deceiving. Even if the glans is keratinized, there is still a mucous and open urethra to consider.

      So far there is no scientifically proven mechanism by which circumcision reduces the risk of HIV. Every paper written on the subject is rich in conditional words: "may", "could", "suggests"... Just last week the media recycled the 2010 story about how circumcision alters the microbiome of the penis reducing the bacteria, reducing the chances of inflammation, and again recycling the Langerhans cells as targets for the virus. But if you read again beyond the title, you will find the conditional words that I'm talking about: "may explain", "suggests"...

      The theory of Langerhans cells as target and entry point for the virus was contradicted by deWitte et al in 2007:

      The article from Scientific American repeats Valiere Alcena's hypothesis of the microtears in the inner foreskin and refers to the target cells (the same Langerhans cells that I already discussed). It also fails to discuss the methodological problems in the 3 RCTs or Mr. Ronald Gray's bias.

      The article from PLOS Medicine at least acknowledges some of the issues of the trials, the selection bias and the ethical issue that put many people at risk, including spouses and potential partners of HIV+ participants.

      There is no proven biological cause for circumcision as prevention of HIV.

      And perhaps you have heard of a recent Belgian survey:

      and a Danish survey from 2011:

      both of which found orgasm difficulties, sexual difficulties, dyspareunia (pain during sex) for circumcised men and their partners.

      Oh and perhaps you may have heard of Rebecca Stallings et al, "For better or worse", a study that unwillingly found lower prevalence of HIV among circumcised women in Tanzania. I remember another two studies finding similar conclusions. But no number of studies will lead the World Health Organization to promote female circumcision (AKA female genital mutilation) as a preventive measure.

      So we should stick to what actually works: treating HIV+ people, focusing on high risk individuals, promoting education, and researching some of the actual paths to a positive cure.

    2. Dreamer, I greatly appreciate your very wise comments and links to resources, regarding the idea that circumcision prevents HIV. Ever since Americans first started making that suggestion, back in the 80s, I have been amazed at how totally irresponsible such a suggestion is. I have wondered how much of America's high rates of HIV, compared to other industrialized countries, is due to the false sense of security from that suggestion. On a side note, I've also wondered how many American women end up with cervical cancer or precancerous condition of the cervix (something else America has very high rates of) because they believed they were protected because their male partners were circumcised.

      What I would like to see is a case-controlled study comparing rates of HIV among circumcised American men, to those among intact American men, or intact men from other countries, such as those in Europe, with similar access to things like indoor plumbing, adequate diets, access to health care, etc. as well as similar sexual practices. Comparing American men to groups of African men whose lives are different in many, many ways, may give fans of infant circumcision more excuses to try to justify what they've all ready been doing, but it certainly doesn't provide any information that is useful in preventing the spread of HIV/AIDS!

      One more thing I feel inclined to comment on is the idea that intact men get tears in the foreskin which increase the likelihood of contracting HIV. I question whether those who make that claim have any first hand experience with a healthy intact foreskin (as opposed to one that was damaged by forcible retraction in infancy and childhood). My husband of 27 years was intact and I have also raised three intact sons and one circumcised son (adopted all ready circumcised), to adulthood, as well as having studied the issue, in depth, since the late 1970s. I think I have a pretty good basic understanding of the anatomy of it, as well as some of the effects of circumcision. That is very flexible, very resilient tissue. It is very rare for an undamaged foreskin not to easily retract by puberty, and those few who don't can usually be treated without amputation. Another possibility is that some American men have had their foreskins damaged by forceful retraction when they were infants and/or children. If they were injured often enough, there may be scar tissue that impedes the function of the foreskin during intercourse and may include tears in the skin. Of course, that would be prevented by just refraining from damaging a child's intact penis! How easy is that?

  2. Circumcision in no way protects against HIV.

  3. A refreshingly thoughtful thread. If you haven't already, please read the works of Morten Frisch, a Danish researcher whose 2015 study found a statistical link between circumcision at birth or in early infancy and autism spectrum disorder. Boys circumcised had a 46% higher incidence of this grave condition. Frisch revealed correlation, not cause. However, many animal and human studies have established that pain early in life can permanently alter the brains' response to stress, a prime feature of ASD. To my knowledge, the AMA, American Academy of Pediatricians, NIH, CDC, nor any major American health-related organization has commented publicly on Frisch's study. Frisch also conducted an earlier study which found a higher rate (11%)of heterosexual partners failing to achieve satisfying sex when the male is circumcised than when he is intact (4%).