The DSM-IV-TR criteria was criticized simultaneously for being over-inclusive, as well as under-inclusive. Though most researchers distinguish between child molesters and pedophiles, Studer and Aylwin argue that the DSM criteria are over-inclusive because all acts of child molestation warrant the diagnosis. A child molester satisfies criteria A because of the behavior involving sexual activity with prepubescent children and criteria B because the individual has acted on those urges. Furthermore, they argue that it also is under-inclusive in the case of individuals who do not act upon it and are not distressed by it. The latter point has also been made by several other researchers who have remarked that a so-called "contented pedophile"—an individual who fantasizes about having sex with a child and masturbates to these fantasies, but does not commit child sexual abuse, and who does not feel subjectively distressed afterward—does not meet the DSM-IV-TR criteria for pedophilia, because this person does not meet Criterion B. A large-scale survey about usage of different classification systems showed that the DSM classification is only rarely used. As an explanation, it was suggested that the under-inclusiveness, as well as a lack of validity, reliability and clarity might have led to the rejection of the DSM classification.

Ray Blanchard, an American-Canadian sexologist known for his research studies on pedophilia, addressed (in his literature review for the DSM-5) the aforementioned objections to the DSM-IV-TR, and proposed a general solution applicable to all paraphilias. This meant namely a distinction between "paraphilia" and "paraphilic disorder". The latter term is proposed to identify the diagnosable mental disorder which meets Criterion A and B, whereas an individual who does not meet Criterion B can be ascertained but "not" diagnosed as having a paraphilia. Blanchard and a number of his colleagues also proposed that hebephilia become a diagnosable mental disorder under the DSM-5 to resolve the physical development overlap between pedophilia and hebephilia by combining the categories under "pedophilic disorder", but with specifiers on which age range (or both) is the primary interest. The proposal for hebephilia was rejected by the American Psychiatric Association, but the distinction between "paraphilia" and "paraphilic disorder" was implemented.

The American Psychiatric Association stated that "[i]n the case of pedophilic disorder, the notable detail is what wasn't revised in the new manual. Although proposals were discussed throughout the DSM-5 development process, diagnostic criteria ultimately remained the same as in DSM-IV TR" and that "[o]nly the disorder name will be changed from pedophilia to pedophilic disorder to maintain consistency with the chapter’s other listings." If hebephilia had been accepted as a DSM-5 diagnosable disorder, it would have been similar to the ICD-10 definition of pedophilia that already includes early pubescents, and would have raised the minimum age required for a person to be able to be diagnosed with pedophilia from 16 years to 18 years (with the individual needing to be at least 5 years older than the minor).

O'Donohue, however, suggests that the diagnostic criteria for pedophilia be simplified to the attraction to children alone if ascertained by self-report, laboratory findings, or past behavior. He states that any sexual attraction to children is pathological and that distress is irrelevant, noting "this sexual attraction has the potential to cause significant harm to others and is also not in the best interests of the individual." Also arguing for behavioral criteria in defining pedophilia, Howard E. Barbaree and Michael C. Seto disagreed with the American Psychiatric Association's approach in 1997 and instead recommended the use of actions as the sole criterion for the diagnosis of pedophilia, as a means of taxonomic simplification.

The "Diagnostic and Statistical Manual of Mental Disorders" 5th edition (DSM-5) has a significantly larger diagnostic features section for pedophilia than the previous DSM version, the DSM-IV-TR, and states, "The diagnostic criteria for pedophilic disorder are intended to apply both to individuals who freely disclose this paraphilia and to individuals who deny any sexual attraction to prepubertal children (generally age 13 years or younger), despite substantial objective evidence to the contrary." Like the DSM-IV-TR, the manual outlines specific criteria for use in the diagnosis of this disorder. These include the presence of sexually arousing fantasies, behaviors or urges that involve some kind of sexual activity with a prepubescent child (with the diagnostic criteria for the disorder extending the cut-off point for prepubescence to age 13) for six months or more, or that the subject has acted on these urges or suffers from distress as a result of having these feelings. The criteria also indicate that the subject should be 16 or older and that the child or children they fantasize about are at least five years younger than them, though ongoing sexual relationships between a 12- to 13-year-old and a late adolescent are advised to be excluded. A diagnosis is further specified by the sex of the children the person is attracted to, if the impulses or acts are limited to incest, and if the attraction is "exclusive" or "nonexclusive".

The ICD-10 defines pedophilia as "a sexual preference for children, boys or girls or both, usually of prepubertal or early pubertal age". Like the DSM, this system's criteria require that the person be at least 16 years of age or older before being diagnosed as a pedophile. The person must also have a persistent or predominant sexual preference for prepubescent children at least five years younger than them.

Several terms have been used to distinguish "true pedophiles" from non-pedophilic and non-exclusive offenders, or to distinguish among types of offenders on a continuum according to strength and exclusivity of pedophilic interest, and motivation for the offense (see child sexual offender types). Exclusive pedophiles are sometimes referred to as "true pedophiles." They are sexually attracted to prepubescent children, and only prepubescent children. Showing no erotic interest in adults, they can only become sexually aroused while fantasizing about or being in the presence of prepubescent children, or both. Non-exclusive offenders—or "non-exclusive pedophiles"—may at times be referred to as "non-pedophilic" offenders, but the two terms are not always synonymous. Non-exclusive offenders are sexually attracted to both children and adults, and can be sexually aroused by both, though a sexual preference for one over the other in this case may also exist. If the attraction is a sexual preference for prepubescent children, such offenders are considered pedophiles in the same vein as exclusive offenders.

Neither the DSM nor the ICD-10 diagnostic criteria require actual sexual activity with a prepubescent youth. The diagnosis can therefore be made based on the presence of fantasies or sexual urges even if they have never been acted upon. On the other hand, a person who acts upon these urges yet experiences no distress about their fantasies or urges can also qualify for the diagnosis. "Acting" on sexual urges is not limited to overt sex acts for purposes of this diagnosis, and can sometimes include indecent exposure, voyeuristic or frotteuristic behaviors, or masturbating to child pornography. Often, these behaviors need to be considered in-context with an element of clinical judgment before a diagnosis is made. Likewise, when the patient is in late adolescence, the age difference is not specified in hard numbers and instead requires careful consideration of the situation.

Ego-dystonic sexual orientation () includes people who acknowledge that they have a sexual preference for prepubertal children, but wish to change it due to the associated psychological or behavioral problems (or both).

When the WHO removed the diagnosis of homosexuality as a mental disorder in ICD-10, it included the diagnosis of "ego-dystonic sexual orientation" under "Psychological and behavioural disorders associated with sexual development and orientation". The WHO's ICD-10 diagnoses ego-dystonic sexual orientation thus:

The gender identity or sexual preference (heterosexual, homosexual, bisexual, or prepubertal) is not in doubt, but the individual wishes it were different because of associated psychological and behavioural disorders, and may seek treatment in order to change it. ()

The WHO notes that for codes under F66: "Sexual orientation by itself is not to be regarded as a disorder."

Patients are sometimes still diagnosed as having this problem. This is often a result of unfavorable and intolerant attitudes of the society or a conflict between sexual urges and religious belief systems.

The American Psychiatric Association permits a diagnosis of "gender dysphoria" if the criteria in the DSM-5 are met. The DSM-5 moved this diagnosis out of the sexual disorders category and into a category of its own. The DSM-5 states that at least two of the criteria for gender dysphoria must be experienced for at least six months' duration in adolescents or adults for diagnosis. The diagnosis was renamed from "Gender Identity Disorder" to "Gender Dysphoria", after criticisms that the former term was stigmatizing. Subtyping by sexual orientation was deleted. The diagnosis for children was separated from that for adults, as "gender dysphoria in children". The creation of a specific diagnosis for children reflects the lesser ability of children to have insight into what they are experiencing, or ability to express it in the event that they have insight.

The International Classification of Diseases (ICD-10) list three diagnostic criteria for "transsexualism" (F64.0): Uncertainty about gender identity which causes anxiety or stress is diagnosed as sexual maturation disorder, according to the ICD-10.

Psychosexual disorders can vary greatly in severity and treatability. Medical professionals and licensed therapists are necessary in diagnosis and treatment plans. Treatment can vary from therapy to prescription medication. Sex therapy, behavioral therapy, and group therapy may be helpful to those suffering distress from sexual dysfunction. More serious sexual perversions may be treated with androgen blockers or selective serotonin reuptake inhibitors (SSRIs) to help restore hormonal and neurochemical balances.

Most psychologists believe that paraphilic sexual interests cannot be altered. Instead, the goal of therapy is normally to reduce the person's discomfort with their paraphilia and limit any criminal behavior. Both psychotherapeutic and pharmacological methods are available to these ends.

Cognitive behavioral therapy, at times, can help people with paraphilias develop strategies to avoid acting on their interests. Patients are taught to identify and cope with factors that make acting on their interests more likely, such as stress. It is currently the only form of psychotherapy for paraphilias supported by evidence.

Antiandrogens are used in more severe cases. Similar to physical castration, they work by reducing androgen levels, and have thus been described as chemical castration. The antiandrogen cyproterone acetate has been shown to substantially reduce sexual fantasies and offending behaviors. Medroxyprogesterone acetate and gonadotropin-releasing hormone agonists (such as leuprolide acetate) have also been used to lower sex drive. Due to the side effects, the World Federation of Societies of Biological Psychiatry recommends that hormonal treatments only be used when there is a serious risk of sexual violence, or when other methods have failed. Surgical castration has largely been abandoned because these pharmacological alternatives are similarly effective and less invasive.

The question of whether to counsel young children to be happy with their assigned sex, or to encourage them to continue to exhibit behaviors that do not match their assigned sex—or to explore a transsexual transition—is controversial. Some clinicians report that a significant proportion of young children diagnosed with gender dysphoria later do not exhibit any dysphoria.

Professionals who treat gender identity disorder in children have begun to refer and prescribe hormones, known as a puberty blocker, to delay the onset of puberty until a child is believed to be old enough to make an informed decision on whether hormonal gender reassignment leading to surgical gender reassignment will be in that person's best interest.

There are many ways a person may go about receiving therapy for ego-dystonic sexual orientation associated with homosexuality. There is no known therapy for other types of ego-dystonic sexual orientations. Therapy can be aimed at changing sexual orientation, sexual behaviour, or helping a client become more comfortable with their sexual orientation and behaviours. Human rights groups have accused some countries of performing these treatments on egosyntonic homosexuals. One survey suggested that viewing the same-sex activities as compulsive facilitated commitment to a mixed-orientation marriage and to monogamy. Treatment may include sexual orientation change efforts or treatment to alleviate the stress. In addition, some people seek non-professional methods, such as religious counselling or attendance in an ex-gay group.

In the DSM-5 all paraphilia disorders can be diagnosed by two main criteria that are referred to criteria A and criteria B respectively. The A and B criteria include a duration in which the behavior must be present for (typically 6 months) and specific details of actions or thoughts that are correlated specifically with the respective disorder being diagnosed.

In the DSM-5, male hypoactive sexual desire disorder is characterized by "persistently or recurrently deficient (or absent) sexual/erotic thoughts or fantasies and desire for sexual activity", as judged by a clinician with consideration for the patient's age and cultural context. Female sexual interest/arousal disorder is defined as a "lack of, or significantly reduced, sexual interest/arousal", manifesting as at least three of the following symptoms: no or little interest in sexual activity, no or few sexual thoughts, no or few attempts to initiate sexual activity or respond to partner's initiation, no or little sexual pleasure/excitement in 75%-100% of sexual experiences, no or little sexual interest in internal or external erotic stimuli, and no or few genital/nongenital sensations in 75%-100% of sexual experiences.

For both diagnoses, symptoms must persist for at least six months, cause clinically significant distress, and not be better explained by another condition. Simply having lower desire than one's partner is not sufficient for a diagnosis. Self-identification of a lifelong lack of sexual desire as asexuality precludes diagnosis.

"Sex reassignment therapy" (SRT) is an umbrella term for all medical treatments related to sex reassignment of both transgender and intersex people.

Individuals make different choices regarding sex reassignment therapy, which may include female-to-male or male-to-female hormone replacement therapy (HRT) to modify secondary sex characteristics, sex reassignment surgery (such as orchiectomy) to alter primary sex characteristics, chest surgery such as top surgery or breast augmentation, or, in the case of trans women, a trachea shave, facial feminization surgery or permanent hair removal.

To obtain sex reassignment therapy, transsexual people are generally required to undergo a psychological evaluation and receive a diagnosis of gender identity disorder in accordance with the Standards of Care (SOC) as published by the World Professional Association for Transgender Health. This assessment is usually accompanied by counseling on issues of adjustment to the desired gender role, effects and risks of medical treatments, and sometimes also by psychological therapy. The SOC are intended as guidelines, not inflexible rules, and are intended to ensure that clients are properly informed and in sound psychological health, and to discourage people from transitioning based on unrealistic expectations.

HSDD, like many sexual dysfunctions, is something that people are treated for in the context of a relationship. Theoretically, one could be diagnosed with, and treated for, HSDD without being in a relationship. However, relationship status is the most predictive factor accounting for distress in women with low desire and distress is required for a diagnosis of HSDD. Therefore, it is common for both partners to be involved in therapy. Typically, the therapist tries to find a psychological or biological cause of the HSDD. If the HSDD is organically caused, the clinician may try to deal with that. If the clinician believes it is rooted in a psychological problem, they may recommend therapy for that. If not, treatment generally focuses more on relationship and communication issues, improved communication (verbal and nonverbal), working on non-sexual intimacy, or education about sexuality may all be possible parts of treatment. Sometimes problems occur because people have unrealistic perceptions about what normal sexuality is and are concerned that they do not compare well to that, and this is one reason why education can be important. If the clinician thinks that part of the problem is a result of stress, techniques may be recommended to more effectively deal with that. Also, it can be important to understand why the low level of sexual desire is a problem for the relationship because the two partners may associate different meaning with sex but not know it.

In the case of men, the therapy may depend on the subtype of HSDD. Increasing the level of sexual desire of a man with lifelong/generalized HSDD is unlikely. Instead the focus may be on helping the couple to adapt. In the case of acquired/generalized, it is likely that there is some biological reason for it and the clinician may attempt to deal with that. In the case of acquired/situational, some form of psychotherapy may be used, possibly with the man alone and possibly together with his partner.

Sadomasochism is the giving or receiving pleasure from acts involving the receipt or infliction of pain or humiliation. Practitioners of sadomasochism may seek sexual gratification from their acts. While the terms sadist and masochist refer respectively to one who enjoys giving or receiving pain, practitioners of sadomasochism may switch between activity and passivity.

The abbreviation S&M is often used for sadomasochism, although practitioners themselves normally remove the ampersand and use the acronym S-M or SM or S/M when written throughout the literature. Sadomasochism is not considered a clinical paraphilia unless such practices lead to clinically significant distress or impairment for a diagnosis. Similarly, sexual sadism within the context of mutual consent, generally known under the heading BDSM, is distinguished from non-consensual acts of sexual violence or aggression.

Biphobia is aversion toward bisexuality and toward bisexual people as a social group or as individuals. It can take the form of denial that bisexuality is a genuine sexual orientation, or of negative stereotypes about people who are bisexual (such as the beliefs that they are promiscuous or dishonest). People of any sexual orientation can experience or perpetuate biphobia, and it is a source of social discrimination against bisexual people.

Zoophilia is a paraphilia involving a sexual fixation on non-human animals. Bestiality is cross-species sexual activity between human and non-human animals. The terms are often used interchangeably, but some researchers make a distinction between the attraction (zoophilia) and the act (bestiality).

Although sex with animals is not outlawed in some countries, in most countries, bestiality is illegal under animal abuse laws or laws dealing with buggery or crimes against nature.

Transsexualism appears in the International Statistical Classification of Diseases and Related Health Problems (ICD, currently in its tenth edition). The ICD-10 incorporates "transsexualism", "dual role transvestism," and "gender identity disorder of childhood" into its gender identity disorder category. It defines transsexualism as "[a] desire to live and be accepted as a member of the opposite sex, usually accompanied by a sense of discomfort with, or inappropriateness of, one's anatomic sex, and a wish to have surgery and hormonal treatment to make one's body as congruent as possible with one's preferred sex."

Historically, transsexualism has also been included in the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders" (DSM). With the DSM-5, transsexualism was removed as a diagnosis, and a diagnosis of gender dysphoria was created in its place. This change was made to reflect the consensus view by members of the APA that transsexuality is not in and of itself a disorder and that transsexual people should not be stigmatized unnecessarily. By including a diagnosis for gender dysphoria, transsexual people are still able to access medical care through the process of transition.

Similarly, the World Professional Association for Transgender Health (WPATH), and many transsexual people, have recommended the removal of transsexualism from the mental health chapter of the upcoming ICD, ICD-11 (due to be released in 2018). They argue that at least some mental health professionals are being insensitive by labelling transsexualism as "a disease", rather than the inborn trait which those who have it believe it to be. Principle 18 of The Yogyakarta Principles, a document of international human rights law, opposes such diagnosis as mental illness as medical abuse.

The current diagnosis for transsexual people who present themselves for medical treatment is gender dysphoria (leaving out those who have sexual identity disorders without gender concerns). According to the "Standards of care" formulated by the World Professional Association for Transgender Health (WPATH), formerly the Harry Benjamin International Gender Dysphoria Association, this diagnostic label is often necessary to obtain sex reassignment therapy with health insurance coverage, and the designation of gender identity disorders as mental disorders is not a license for stigmatization or for the deprivation of gender patients' civil rights.

In 2009 Amy Marsh, a clinical sexologist, surveyed the twenty-one English-speaking members of Erika Eiffel's 40-strong OS Internationale about their experiences. About half reported autism spectrum disorders: six had been diagnosed, four were affected but not diagnosed, and three of the remaining nine reported having "some traits." According to Marsh, "The emotions and experiences reported by OS people correspond to general definitions of sexual orientation," such as that in an APA article "on sexual orientation and homosexuality ... [which] refers to sexual orientation as involving 'feelings and self concept.'"

BDSM is a variety of often erotic practices or roleplaying involving bondage, discipline, dominance and submission, sadomasochism, and other related interpersonal dynamics. Given the wide range of practices, some of which may be engaged in by people who do not consider themselves as practicing BDSM, inclusion in the BDSM community or subculture is usually dependent upon self-identification and shared experience.

The term "BDSM" is first recorded in a Usenet posting from 1991, and is interpreted as a combination of the abbreviations B/D (Bondage and Discipline), D/s (Dominance and submission), and S/M (Sadism and Masochism). BDSM is now used as a catch-all phrase covering a wide range of activities, forms of interpersonal relationships, and distinct subcultures. BDSM communities generally welcome anyone with a non-normative streak who identifies with the community; this may include cross-dressers, body modification enthusiasts, animal roleplayers, rubber fetishists, and others.

Activities and relationships within a BDSM context are often characterized by the participants taking on complementary, but unequal roles; thus, the idea of informed consent of both the partners is essential. The terms "submissive" and "dominant" are often used to distinguish these roles: the dominant partner ("dom") takes psychological control over the submissive ("sub"). The terms "top" and "bottom" are also used: the top is the instigator of an action while the bottom is the receiver of the action. The two sets of terms are subtly different: for example, someone may choose to act as bottom to another person, for example, by being whipped, purely recreationally, without any implication of being psychologically dominated by them, or a submissive may be ordered to massage their dominant partner. Despite the bottom performing the action and the top receiving they have not necessarily switched roles.

The abbreviations "sub" and "dom" are frequently used instead of "submissive" and "dominant". Sometimes the female-specific terms "mistress", "domme" or "dominatrix" are used to describe a dominant woman, instead of the gender-neutral term "dom". Individuals who can change between top/dominant and bottom/submissive roles—whether from relationship to relationship or within a given relationship—are known as "switches". The precise definition of roles and self-identification is a common subject of debate within the community.

Transmisogyny (sometimes trans-misogyny) is the intersection of transphobia and misogyny. Transphobia is defined as "the irrational fear of, aversion to, or discrimination against transgender or transsexual people". Misogyny is defined as "a hatred of women". Therefore, transmisogyny includes negative attitudes, hate, and discrimination of transgender or transsexual individuals who fall on the feminine side of the gender spectrum, particularly transgender women. The term was coined by Julia Serano in her 2007 book "Whipping Girl" and used to describe the unique discrimination faced by trans women because of "the assumption that femaleness and femininity are inferior to, and exist primarily for the benefit of, maleness and masculinity", and the way that transphobia intensifies the misogyny faced by trans women (and vice versa). It is said many trans women experience an additional layer of misogyny in the form of fetishization; Serano talks about how society views trans women in certain ways that sexualize them, such as them transitioning for sexual reasons, or ways where they’re seen as sexually promiscuous.Transmisogyny is a central concept in transfeminism and is commonly referenced in intersectional feminist theory. That trans women's femaleness (rather than only their femininity) is a source of transmisogyny is denied by certain radical feminists, who claim that trans women are not female.

Males with late onset gender dysphoria "frequently" display transvestic fetishism.

Some male transvestic fetishists collect women's clothing, e.g. panties, nightgowns, babydolls, bridal gowns, slips, brassieres, and other types of nightwear, lingerie, stockings, pantyhose, shoes, and boots, items of a distinct feminine look and feel. They may dress in these feminine garments and take photographs of themselves while living out their fantasies.

According to DSM-IV, this fetishism was limited to heterosexual men; however, DSM-5 does not have this restriction, and opens it to women and men with this interest, regardless of their sexual orientation.

There are two key criteria before a psychiatric diagnosis of "transvestic fetishism" is made:

1. Individuals must be sexually aroused by the act of cross-dressing.

2. Individuals must experience significant distress or impairment – socially or occupationally – because of their behavior.

Object sexuality or objectophilia is a form of sexuality focused on particular inanimate objects. Those individuals with this expressed preference may feel strong feelings of attraction, love, and commitment to certain items or structures of their fixation. For some, sexual or even close emotional relationships with humans are incomprehensible. Some object-sexual individuals also often believe in animism, and sense reciprocation based on the belief that objects have souls, intelligence, and feelings, and are able to communicate.

Lesbophobia (sometimes lesbiphobia) comprises various forms of negativity towards lesbians as individuals, as couples, or as a social group. Based on the categories of sex, sexual orientation, lesbian identity, and gender expression, this negativity encompasses prejudice, discrimination, and abuse, in addition to attitudes and feelings ranging from disdain to hostility. As such, lesbophobia is sexism against women that intersects with homophobia and vice versa.

Macrophilia is a fascination with or a sexual fantasy involving giants, more commonly expressed as giantesses (female giants). It is typically a male fantasy, with the male playing the "smaller" part—entering, being dominated, or being eaten by the larger woman. Others involve partners who naturally have a significant difference in size.

Sexual maturation disorder is a disorder of anxiety or depression related to an uncertainty about one's gender identity or sexual orientation. The World Health Organization (WHO) lists sexual maturation disorder in the ICD-10, under "Psychological and behavioural disorders associated with sexual development and orientation".

Sexual orientation, by itself, is not a disorder and is not classified under this heading. It differs from ego-dystonic sexual orientation where the sexual orientation or gender identity is repressed or denied.