<unk>  can be classified into four categories:<unk>  desire disorders, arousal disorders, orgasm disorders, and pain disorders. Dysfunction among men and women are studied in the fields of andrology and gynecology respectively.<unk>  desire disorders<unk>  desire disorders or decreased libido are characterized by a lack of<unk>  desire, libido for<unk>  activity, or<unk>  fantasies for some time. The condition ranges from a general lack of<unk>  desire to a lack of<unk>  desire for the current partner. The condition may start after a period of normal<unk>  functioning, or the person may always have had an absence or a lesser intensity of<unk>  desire. The causes vary considerably but include a decrease in the production of normal estrogen in women, or testosterone in both men and women. Other causes may be aging, fatigue, pregnancy, medications (such as SSRIs), or psychiatric conditions, such as depression and anxiety. While many causes of low<unk>  desire are cited, only a few of these have ever been the object of empirical research.<unk>  arousal disorders<unk>  arousal disorders were previously known as frigidity in women and impotence in men, though these have now been replaced with less judgmental terms. Impotence is now known as erectile dysfunction, and frigidity has been replaced with a number of terms describing specific problems that can be broken down into four categories as described by the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders: lack of desire, lack of arousal, pain during intercourse, and lack of orgasm. For both men and women, these conditions can manifest themselves as an aversion to and avoidance of<unk>  contact with a partner. In men, there may be partial or complete failure to attain or maintain an erection, or a lack of<unk>  excitement and pleasure in<unk>  activity. There may be physiological origins to these disorders, such as decreased blood flow or lack of vaginal lubrication. Chronic disease and the partners' relationship can also contribute to dysfunction. Additionally, postorgasmic illness syndrome (POIS) may cause symptoms when aroused, including adrenergic-type presentation: rapid breathing, paresthesia, palpitations, headaches, aphasia, nausea, itchy eyes, fever, muscle pain and weakness, and fatigue. From the onset of arousal, symptoms can persist for up to a week in patients. The cause of this condition is unknown; however, it is believed to be a pathology of either the immune system or autonomic nervous systems. It is defined as a rare disease by the National Institute of Health, but the prevalence is unknown. It is not thought to be psychiatric in nature, but it may present as anxiety relating to coital activities and may be incorrectly diagnosed as such. There is no known cure or treatment. Erectile dysfunction Erectile dysfunction (ED), or impotence, is a<unk>  characterized by the inability to develop or maintain an erection of the penis. There are various underlying causes of ED, including damage to anatomical structures, psychological causes, medical disease, and drug use. Many of these causes are medically treatable. Psychological ED can often be treated by almost anything that the patient believes in; there is a very strong placebo effect. Physical damage can be more difficult to treat. One leading physical cause of ED is continual or severe damage taken to the nervi erigentes, which can prevent or delay erection. These nerves course beside the prostate arising from the sacral plexus and can be damaged in prostatic and colorectal surgeries. Diseases are also common causes of erectile dysfunctional. Diseases such as cardiovascular disease, multiple sclerosis, kidney failure, vascular disease, and spinal cord injury can cause erectile dysfunction. Cardiovascular disease can decrease blood flow to penile tissues, making it difficult to develop or maintain an erection. Due to the shame and embarrassment felt by some sufferers of erectile dysfunction, the subject was taboo for a long time and is the focus of many urban legends. Folk remedies have long been advocated, with some being advertised widely since the 1930s. The introduction of perhaps the first pharmacologically effective remedy for impotence, sildenafil (trade name Viagra), in the 1990s caused a wave of public attention, propelled in part by the newsworthiness of stories about it and heavy advertising. It is estimated that around 30 million men in the United States and 152 million men worldwide suffer from erectile dysfunction. However, social stigma, low health literacy, and social taboos lead to under reporting which makes an accurate prevalence rate hard to determine. The Latin term impotentia coeundi describes the inability to insert the penis into the vagina, and has been mostly replaced by more precise terms. ED from vascular disease is seen mainly amongst older individuals who have atherosclerosis. Vascular disease is common in individuals who smoke or have diabetes, peripheral vascular disease, or hypertension. Any time blood flow to the penis is impaired, ED can occur. Drugs are also a cause of erectile dysfunction. Individuals who take drugs that lower blood pressure, antipsychotics, antidepressants, sedatives, narcotics, antacids, or alcohol can have problems with<unk>  function and loss of libido. Hormone deficiency is a relatively rare cause of erectile dysfunction. In individuals with testicular failure, as in Klinefelter syndrome, or those who have had radiation therapy, chemotherapy, or childhood exposure to the mumps virus, the testes may fail to produce testosterone. Other hormonal causes of erectile failure include brain tumors, hyperthyroidism, hypothyroidism, or adrenal gland disorders. Orgasm disorders Anorgasmia Anorgasmia is classified as persistent delays or absence of orgasm following a normal<unk>  excitement phase in at least 75% of<unk>  encounters. The disorder can have physical, psychological, or pharmacological origins. SSRI antidepressants are a common pharmaceutical culprit, as they can delay orgasm or eliminate it entirely. A common physiological cause of anorgasmia is menopause; one in three women report problems obtaining an orgasm during<unk>  stimulation following menopause. Premature ejaculation Premature ejaculation is when ejaculation occurs before the partner achieves orgasm, or a mutually satisfactory length of time has passed during intercourse. There is no correct length of time for intercourse to last, but generally, premature ejaculation is thought to occur when ejaculation occurs in under two minutes from the time of the insertion of the penis. For a diagnosis, the patient must have a chronic history of premature ejaculation, poor ejaculatory control, and the problem must cause feelings of dissatisfaction as well as distress for the patient, the partner, or both. Premature ejaculation has historically been attributed to psychological causes, but newer theories suggest that premature ejaculation may have an underlying neurobiological cause that may lead to rapid ejaculation. Post-orgasmic disorders Post-orgasmic disorders cause symptoms shortly after orgasm or ejaculation. Post-coital tristesse (PCT) is a feeling of melancholy and anxiety after<unk>  intercourse that lasts for up to two hours.<unk>  headaches occur in the skull and neck during<unk>  activity, including masturbation, arousal or orgasm. In men, POIS causes severe muscle pain throughout the body and other symptoms immediately following ejaculation. These symptoms last for up to a week. Some doctors speculate that the frequency of POIS "in the population may be greater than has been reported in the academic literature", and that many POIS sufferers are undiagnosed. POIS may involve adrenergic symptoms: rapid breathing, paresthesia, palpitations, headaches, aphasia, nausea, itchy eyes, fever, muscle pain and weakness, and fatigue. The etiology of this condition is unknown; however, it is believed to be a pathology of either the immune system or autonomic nervous systems. It is defined as a rare disease by the NIH, but the prevalence is unknown. It is not thought to be psychiatric in nature, but it may present as anxiety relating to coital activities and thus may be incorrectly diagnosed as such. There is no known cure or treatment. Dhat syndrome is another condition which occurs in men: it is a culture-bound syndrome which causes anxious and dysphoric mood after sex. It is distinct from the low-mood and concentration problems (acute aphasia) seen in POIS.<unk>  pain disorders<unk>  pain disorders in women include dyspareunia (painful intercourse) and vaginismus (an involuntary spasm of the muscles of the vaginal wall that interferes with intercourse). Dyspareunia may be caused by vaginal dryness. Poor lubrication may result from insufficient excitement and stimulation, or from hormonal changes caused by menopause, pregnancy, or breastfeeding. Irritation from contraceptive creams and foams can also cause dryness, as can fear and anxiety about sex. It is unclear exactly what causes vaginismus, but it is thought that past<unk>  trauma (such as rape or abuse) may play a role. Another female<unk>  pain disorder is vulvodynia, or vulvar vestibulitis when localized to the Vulval vestibule. In this condition, women experience burning pain during sex, which seems to be related to problems with the skin in the vulvar and vaginal areas. Its cause is unknown. In men, structural abnormalities of the penis like Peyronie's disease can make<unk>  intercourse difficult and/or painful. The disease is characterized by thick fibrous bands in the penis that lead to excessive curvature during erection. It has an incidence estimated at 0.4–3% or
Sexual dysfunction
Irregular menstruation
Ejaculation disorders
Urinary incontinence
Erectile dysfunction
Dyspareunia
Anorectal disorder
Delayed ejaculation