Surgical intervention for a number of conditions may remove anatomical structures necessary to erection, damage nerves, or impair blood supply. Erectile dysfunction is a common complication of treatments for prostate cancer, including prostatectomy and destruction of the prostate by external beam radiation, although the prostate gland itself is not necessary to achieve an erection. As far as inguinal hernia surgery is concerned, in most cases, and in the absence of postoperative complications, the operative repair can lead to a recovery of the sexual life of patients with preoperative sexual dysfunction, while, in most cases, it does not affect patients with a preoperative normal sexual life.

ED can also be associated with bicycling due to both neurological and vascular problems due to compression. The increase risk appears to be about 1.7-fold.

Concerns that use of pornography can cause erectile dysfunction have not been substantiated in epidemiological studies according to a recent literature review. However, another review and case studies article maintains that use of pornography does indeed cause erectile dysfunction, and critiques the previously described literature review.

Secondary anorgasmia is close to 50% among males undergoing prostatectomy; 80% among radical prostatectomies. This is a serious adverse result because radical prostatectomies are usually given to younger males who are expected to live more than 10 years. At more advanced ages, the prostate is less likely to grow during that person's remaining lifetime. This is generally caused by damage to the primary nerves serving the penile area, which pass near the prostate gland. Removal of the prostate frequently damages or even completely removes these nerves, making sexual response unreasonably difficult.

Erectile dysfunction from vascular disease is usually seen only amongst elderly individuals who have atherosclerosis. Vascular disease is common in individuals who have diabetes, peripheral vascular disease, hypertension and those who smoke. Any time blood flow to the penis is impaired, erectile dysfunction is the end result.

Hormone deficiency is a relatively rare cause of erectile dysfunction. In individuals with testicular failure like in Klinefelter syndrome, or those who have had radiation therapy, chemotherapy or childhood exposure to mumps virus, the testes may fail and not produce testosterone. Other hormonal causes of erectile failure include brain tumors, hyperthyroidism, hypothyroidism or disorders of the adrenal gland.

Structural abnormalities of the penis like Peyronie's disease can make sexual intercourse difficult. The disease is characterized by thick fibrous bands in the penis which leads to a deformed-looking penis.

Drugs are also a cause of erectile dysfunction. Individuals who take drugs to lower blood pressure, uses antipsychotics, antidepressants, sedatives, narcotics, antacids or alcohol can have problems with sexual function and loss of libido.

Priapism is a painful erection that occurs for several hours and occurs in the absence of sexual stimulation. This condition develops when blood gets trapped in the penis and is unable to drain out. If the condition is not promptly treated, it can lead to severe scarring and permanent loss of erectile function. The disorder occurs in young men and children. Individuals with sickle-cell disease and those who abuse certain medications can often develop this disorder.

Erectile dysfunction is characterized by the regular or repeated inability to obtain or maintain an erection.

The female sexual response system is complex and even today, not fully understood. The most prevalent of female sexual dysfunctions that have been linked to menopause include lack of desire and libido; these are predominantly associated with hormonal physiology. Specifically, it is the decline in serum estrogens that causes these changes in sexual functioning. Androgen depletion may also play a role, but currently this is less clear. The hormonal changes that take place during the menopausal transition have been suggested to affect women's sexual response through several mechanisms, some more conclusive than others.

The condition is sometimes classified as a psychiatric disorder. However, it can also be caused by medical problems such as diabetic neuropathy, multiple sclerosis, genital mutilation, complications from genital surgery, pelvic trauma (such as from a straddle injury caused by falling on the bars of a climbing frame, bicycle or gymnastics beam), hormonal imbalances, total hysterectomy, spinal cord injury, cauda equina syndrome, uterine embolisation, childbirth trauma (vaginal tearing through the use of forceps or suction or a large or unclosed episiotomy), vulvodynia and cardiovascular disease.

A common cause of situational anorgasmia, in both men and women, is the use of anti-depressants, particularly selective serotonin reuptake inhibitors (SSRIs). Though reporting of anorgasmia as a side effect of SSRIs is not precise, studies have found that 17–41% of users of such medications are affected by some form of sexual dysfunction.

Another cause of anorgasmia is opiate addiction, particularly to heroin.

About 15% of women report difficulties with orgasm, and as many as 10% of women in the United States have never climaxed. Only 29% of women always have orgasms with their partner.

The causes of premature ejaculation are unclear. Many theories have been suggested, including that PE was the result of masturbating quickly during adolescence to avoid being caught, of performance anxiety, of an unresolved Oedipal conflict, of passive-aggressiveness, and having too little sex; but there is little evidence to support any of these theories.

Several physiological mechanisms have been hypothesized to contribute to causing premature ejaculation including serotonin receptors, a genetic predisposition, elevated penile sensitivity, and nerve conduction atypicalities.

The nucleus paragigantocellularis of the brain has been identified as having involvement in ejaculatory control. Scientists have long suspected a genetic link to certain forms of premature ejaculation. In one study, 91 percent of men who have had premature ejaculation for their entire lives also had a first-relative with lifelong premature ejaculation. Other researchers have noted that men who have premature ejaculation have a faster neurological response in the pelvic muscles.

PE may be caused by prostatitis or as a drug side effect.

Premature ejaculation is a prevalent sexual dysfunction in men; however, because of the variability in time required to ejaculate and in partners' desired duration of sex, exact prevalence rates of PE are difficult to determine. In the "Sex in America" surveys (1999 and 2008), University of Chicago researchers found that between adolescence and age 59, approximately 30% of men reported having experienced PE at least once during the previous 12 months, whereas about 10 percent reported erectile dysfunction (ED). Although ED is men's most prevalent sex problem after age 60, and may be more prevalent than PE overall according to some estimates, premature ejaculation remains a significant issue that, according to the survey, affects 28 percent of men age 65–74, and 22 percent of men age 75–85. Other studies report PE prevalence ranging from 3 percent to 41 percent of men over 18, but the great majority estimate a prevalence of 20 to 30 percent—making PE a very common sex problem.

There is a common misconception that younger men are more likely to suffer premature ejaculation and that its frequency decreases with age. Prevalence studies have indicated, however, that rates of PE are constant across age groups.

The numbers of women with SCI giving birth and having healthy babies are increasing. Around a half to two-thirds of women with SCI report they might want to have children, and 14–20% do get pregnant at least once. Although female fertility is not usually permanently reduced by SCI, there is a stress response that can happen immediately post-injury that alters levels of fertility-related hormones in the body. In about half of women, menstruation stops after the injury but then returns within an average of five months—it returns within a year for a large majority. After menstruation returns, women with SCI become pregnant at a rate close to that of the rest of the population.

Pregnancy is associated with greater-than-normal risks in women with SCI, among them increased risk of deep vein thrombosis, respiratory infection, and urinary tract infection. Considerations exist such as maintaining proper positioning in a wheelchair, prevention of pressure sores, and increased difficulty moving due to weight gain and changes in center of balance. Assistive devices may need to be altered and medications changed.

For women with injuries above T6, a risk during labor and delivery that threatens both mother and fetus is autonomic dysreflexia, in which the blood pressure increases to dangerous levels high enough to cause potentially deadly stroke. Drugs such as nifedipine and captopril can be used to manage an episode if it occurs, and epidural anesthesia helps although it is not very reliable in women with SCI. Anesthesia is used for labor and delivery even for women without sensation, who may only experience contractions as abdominal discomfort, increased spasticity, and episodes of autonomic dysreflexia. Reduced sensation in the pelvic area means women with SCI usually have less painful delivery; in fact, they may fail to realize when they go into labor. If there are deformities in the pelvis or spine caesarian section may be necessary. Babies of women with SCI are more likely to be born prematurely, and, premature or not, they are more likely to be small for their gestational time.

Men with SCI rank the ability to father children among their highest concerns relating to sexuality. Male fertility is reduced after SCI, due to a combination of problems with erections, ejaculation, and quality of the semen. As with other types of sexual response, ejaculation can be psychogenic or reflexogenic, and the level of injury affects a man's ability to experience each type. As many as 95% of men with SCI have problems with ejaculation (anejaculation), possibly due to impaired coordination of input from different parts of the nervous system. Erection, orgasm, and ejaculation can each occur independently, although the ability to ejaculate seems linked to the quality of the erection, and the ability to orgasm is linked to the ejaculation facility. Even men with complete injuries may be able to ejaculate, because other nerves involved in ejaculation can effect the response without input from the spinal cord. In general, the higher the level of injury, the more physical stimulation the man needs to ejaculate. Conversely, premature or spontaneous ejaculation can be a problem for men with injuries at levels T12–L1. It can be severe enough that ejaculation is provoked by thinking a sexual thought, or for no reason at all, and is not accompanied by orgasm.

Most men have a normal sperm count, but a high proportion of sperm are abnormal; they are less motile and do not survive as well. The reason for these abnormalities is not known, but research points to dysfunction of the seminal vesicles and prostate, which concentrate substances that are toxic to sperm. Cytokines, immune proteins which promote an inflammatory response, are present at higher concentrations in semen of men with SCI, as is platelet-activating factor acetylhydrolase; both are harmful to sperm. Another immune-related response to SCI is the presence of a higher number of white blood cells in the semen.

A number of studies have explored the factors that contribute to female sexual arousal disorder and female orgasmic disorder. These factors include both psychological and physical factors. Psychologically, possible causes of the disorder include the impact of childhood and adolescence experiences and current events – both within the individual and within the current relationship.

A case report of male breast cancer subsequent to bicalutamide-induced gynecomastia has been published. According to the authors, "this is the second confirmed case of breast cancer in association with bicalutamide-induced gynaecomastia (correspondence AstraZeneca)." It is notable, however, that gynecomastia does not seem to increase the risk of breast cancer in men. Moreover, the lifetime incidence of breast cancer in men is approximately 0.1%, the average age of diagnosis of prostate cancer and male breast cancer are similar (around 70 years), and millions of men have been treated with bicalutamide for prostate cancer, all of which are potentially in support of the notion of chance co-occurrences. In accordance, the authors concluded that "causality cannot be established" and that it was "probable that the association is entirely coincidental and sporadic."

There has been little investigation of the impact of individual factors on female sexual dysfunction. Such factors include stress, levels of fatigue, gender identity, health, and other individual attributes and experiences, such as dysfunctional sexual beliefs that may affect sexual desire or response. Over exposure to pornography-style media is also thought to lead to poor body image, self-consciousness and lowered self-esteem. An individual's sexual activity is disrupted by overwhelming emotional distress resulting in inability to attain sexual pleasure. Sexual dysfunction can also occur secondary to major psychiatric disorders, including depression.

Because bicalutamide blocks the , like all antiandrogens, it can interfere with the androgen-mediated sexual differentiation of the genitalia (and brain) during prenatal development. In pregnant rats given bicalutamide at a dosage of 10 mg/kg/day (resulting in circulating drug levels approximately equivalent to two-thirds of human therapeutic concentrations) and above, feminization of male offspring, such as reduced anogenital distance and hypospadias, as well as impotence, were observed. No other teratogenic effects were observed in rats or rabbits receiving up to very high dosages of bicalutamide (that corresponded to up to approximately two times human therapeutic levels), and no teratogenic effects of any sort were observed in female rat offspring at any dosage. As such, bicalutamide is a selective reproductive teratogen in males, and may have the potential to produce undervirilization/sexually ambiguous genitalia in male fetuses.

According to one hypothesis, "POIS is caused by Type-I and Type-IV allergy to the males' own semen". Specifically,

POIS could also be caused by an auto-immune reaction not to semen itself, but to another substance that is released during ejaculation, such as to cytokines.

The allergy hypothesis has been disputed. According to one study, "IgE-mediated semen allergy in men may not be the potential mechanism of POIS".

Studies indicate that dietary patterns may affect development of BPH, but further research is needed to clarify any important relationship. Studies from China suggest that greater protein intake may be a factor in development of BPH. Men older than 60 in rural areas had very low rates of clinical BPH, while men living in cities and consuming more animal protein had a higher incidence. On the other hand, a study in Japanese-American men in Hawaii found a strong negative association with alcohol intake, but a weak positive association with beef intake. In a large prospective cohort study in the US (the Health Professionals Follow-up Study), investigators reported modest associations between BPH (men with strong symptoms of BPH or surgically confirmed BPH) and total energy and protein, but not fat intake. There is also epidemiological evidence linking BPH with metabolic syndrome (concurrent obesity, impaired glucose metabolism and diabetes, high triglyceride levels, high levels of low-density cholesterol, and hypertension).

According to another hypothesis, POIS is caused by a hormone imbalance, such as low progesterone, low cortisol, low testosterone, elevated prolactin, hypothyroidism, or low DHEA.

POIS could be caused by a defect in neurosteroid precursor synthesis. In this case, the same treatment may not be effective for different sufferers. Different sufferers may have different missing precursors, ultimately leading to a deficiency of the same particular neurosteroid, causing similar symptoms.

Certain medications can increase urination difficulties by increasing bladder outlet resistance by increasing smooth muscle tone at the prostate or bladder neck and contribute to LUTS. Alpha-adrenergic agonist medications, such as decongestants with pseudoephedrine can increase bladder outlet resistance. In contrast, calcium channel blockers and anticholinergic medications can worsen urinary retention by promoting bladder muscle relaxation. Diuretic medications such as loop diuretics (e.g., furosemide) or thiazides (e.g., chlorthalidone) can cause or worsen urinary frequency and nighttime awakenings to urinate.

Dr. Mahmood Bhutta, an otorhinolaryngologist at John Radcliffe Hospital, states that sexually induced sneezing may be genetically determined, and may result from the way the central nervous system is wired:

"[T]his reflex demonstrates evolutionary relics in the wiring of a part of the nervous system called the autonomic nervous system. [...] This is the part beyond our control, and which controls things like our heart rate and the amount of light let in by our pupils. [...] Sometimes the signals in this system get crossed, and I think this may be why some people sneeze when they think about sex."

Another possible explanation concerns the existence of erectile tissue in the nose, which may become engorged during sexual arousal, triggering a sneeze.

Gonadectomy at time of diagnosis is the current recommendation for PAIS if presenting with cryptorchidism, due to the high (50%) risk of germ cell malignancy. The risk of malignancy when testes are located intrascrotally is unknown; the current recommendation is to biopsy the testes at puberty, allowing investigation of at least 30 seminiferous tubules, with diagnosis preferably based on OCT3/4 immunohistochemistry, followed by regular examinations. Hormone replacement therapy is required after gonadectomy, and should be modulated over time to replicate the hormone levels naturally present in the body during the various stages of puberty. Artificially induced puberty results in the same, normal development of secondary sexual characteristics, growth spurt, and bone mineral accumulation. Women with PAIS may have a tendency towards bone mineralization deficiency, although this increase is thought to be less than is typically seen in CAIS, and is similarly managed.

The person experiences sneezing as a result of sexual thoughts, arousal, intercourse, or orgasm. Sneezing occurs independent of external nasal stimuli or allergens, and may occur at any point during a sexual experience. Both men and women are affected by the phenomenon.

The annual prevalence in the general population of chronic pelvic pain syndrome is 0.5%. 38% of primary care providers, when presented with a vignette of a man with CPPS, indicate that they have never seen such a patient. However, the overall prevalence of symptoms suggestive of CP/CPPS is 6.3%. The role of the prostate was questioned in the cause of CP/CPPS when both men and women in the general population were tested using the (1) National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) —with the female homolog of each male anatomical term use on questionnaires for female participants— (2) the International Prostate Symptom Score (IPSS), and (3) additional questions on pelvic pain. The prevalence of symptoms suggestive of CPPS in this selected population was 5.7% in women and 2.7% in men, placing in doubt the role of the prostate gland. New evidence suggests that the prevalence of CP/CPPS is much higher in teenage males than once suspected.

The decision of whether to raise an individual with PAIS as a boy or a girl may not be obvious; grades 3 and 4 in particular present with a phenotype that may be difficult to classify as primarily male or female, and some will be incapable of virilization at puberty. Parents of an affected newborn should seek immediate help at a center with an experienced multidisciplinary team, and should avoid gender assignment beforehand. Gender assignment should thereafter be expeditiously decided; current guidelines advise against waiting for the child to decide for his / herself. Key considerations involved in assigning gender include the appearance of the genitalia, the extent to which the child can virilize at puberty, surgical options and the postoperative sexual function of the genitalia, genitoplasty complexity, potential for fertility, and the projected gender identity of the child. The majority of individuals with PAIS are raised male.

Virilization capacity can be assessed by measuring the response to a trial of exogenous androgens; some studies have measured the growth of the phallus in response to exogenous testosterone or dihydrotestosterone, while others have measured the change in sex hormone binding globulin (SHBG) in response to the artificial androgen stanozolol to assess androgen sensitivity. Some experts have cautioned that it remains to be proved that a good response to exogenous androgens in neonates is a good predictor of androgen response at puberty. If a mutation in the AR gene is found, it is important to determine whether the mutation is inherited or de novo (i.e. a somatic mutation); a certain amount of the wild-type androgen receptor will be present in cases of somatic mutation, which can induce virilization at puberty. A genital skin fibroblast study and a human chorionic gonadotropin (hCG) stimulation test may also provide information helpful in the assessment of virilization capacity.

Psychosexual development is influenced by many factors, including the timing, amount, and type of androgen exposure, receptor functionality, and environment, and is thus difficult to predict. Gender identity begins to develop before 3 years of age, although the earliest age at which it can be reliably assessed has yet to be determined. Approximately 25% of individuals with PAIS are dissatisfied with their assigned gender, regardless of being raised as male or female. One study reports that 46,XY individuals born with micropenis and no hypospadias are better off being raised male, despite the success of some being raised female. Studies involving the more ambiguous phenotypic forms of PAIS are less decisive. Homosexuality with respect to assigned gender and atypical gender role behavior are known to occur more frequently in individual with PAIS, and may occur with or without gender dysphoria; neither should be interpreted as an indication of incorrect gender assignment. If an affected child does express feelings of gender dysphoria, the opportunity to explore such feelings with a psychologist experienced in treating intersex conditions should be accommodated. If feelings of gender dysphoria persist, gender reassignment should be initiated, possibly with the aid of a specialist in the field.

In recent years the prognosis for CP/CPPS has improved with the advent of multimodal treatment, phytotherapy, protocols aimed at quieting the pelvic nerves through myofascial trigger point release and anxiety control, and chronic pain therapy.

Phallophobia in its narrower sense is a fear of the erect penis and in a broader sense an excessive aversion to masculinity.