The short answer to this question, at the present time, is no.
Do a substantial number of individuals struggle to regulate their sexual thoughts, urges, and behaviors leading to significant distress and negative consequences? Yes, and I have worked with hundreds of these patients over the past decade who have sought help for what I prefer to label as hypersexual behavior (rather than sex addiction). In an effort to further understand this population of individuals, I accepted the assignment to be the principal investigator for the UCLA field trial that studied the “Hypersexual Disorder” criteria that were proposed (but ultimately excluded) for the DSM-5.  Although the rationale for this decision rendered by the American Psychiatric Association is complex,  there are a number of issues to consider before characterizing a phenomenon as a disorder.
Defining a Disorder
Pathologizing any phenomenon has significant ramifications for health care providers, the corporate sector (e.g., insurance and pharmacological companies), the scientific community, the legal field, allocation of public funding, social policies, and the obvious implications for patients having the stigma of a diagnosis. Thus, it is a serious undertaking to evaluate whether hypersexuality constitutes a disorder. Admittedly, how a disorder should be characterized and defined has been an ongoing subject of significant controversy among psychiatry and the broader mental health field. This debate was intensified during the development of the DSM-5 creating a volatile climate for the hypersexual disorder (HD) proposal from its inception.
When all of these domains are evaluated, the phenomenon of hypersexual behavior has insufficient data to make a convincing argument that it meets the high standard required to constitute a disorder.-Rory C. Reid
While there are a constellation of issues related to conceptualizing a disorder, the two issues most relevant for hypersexuality are (1) the need to demonstrate a biological dysfunction or how some internal mechanism is failing to perform its natural function and (2) epidemiological data highlighting the onset, clinical course, and way in which hypersexual behavior diverges from what might be considered ‘normal’ sexual activity. In addressing these two issues, scientific research often employs a number of methods including anatomical and functional imaging, molecular genetics, pathophysiology, epidemiology, and neuropsychological testing. When all of these domains are evaluated, the phenomenon of hypersexual behavior has insufficient data to make a convincing argument that it meets the high standard required to constitute a disorder.
Colleagues at Yale, Columbia University, and I have discussed several factors that need to be considered in order for hypersexual behavior to be classified as an addiction or a disorder. We drew comparisons between the vast amounts of data reported in the scientific literature on gambling disorders (which is included for the first time in DSM-5 as a non-substance related disorder classified under “Substance-Related and Addictive Disorders”) compared to the paucity of data gathered in support of hypersexual behavior.  Simply put, despite claims to the contrary, there is not enough research to say that hypersexual behavior (or what’s commonly known as “sex addiction”) is a psychiatric disorder.
Limitations to Brain Imaging Research
While some preliminary data from neuroimaging — those pictures showing how various sections of the brain “light up” in response to desirable substances or situations — suggests parallels between brain responses in substance-related disorders and those occurring in sexually compulsive individuals, these studies are in their infancy, and the methods do not allow inferences about causation. These studies look at relationships but there can be multiple explanations for these associations other than “XYZ is a disorder or an addiction.” Consider a humorous illustration of this concept:
The Japanese drink very little red wine and suffer fewer heart attacks than the British or Americans. Italians drink large amounts of red wine and also suffer fewer heart attacks than the British or Americans. Conclusion: Eat and drink what you like. It appears that speaking English is what kills you!
Some brain imaging studies also neglect a host of potential alternative explanations for the findings. For example, one study observed differences in activation in the frontal lobe between hypersexual subjects compared to a healthy control group but they didn’t assess whether the hypersexual group also had adult attention-deficit hyperactivity disorder which could have also explained these brain differences.  Visual sexual stimuli (such as nude images of women or men) often used in such neuroimaging studies are emotionally stimulating and increase blood flow to multiple brain regions also implicated in reward processing, motivation, vigilance, and attention. Thus, one plausible explanation (rather than characterizing brain responses as evidence of addiction or a disorder) is that the subjects viewing the images found them novel, exciting, or simply just liked sexual pictures.
Despite these shortcomings, neuroimaging is an important tool to gather more information about possible underlying neurobiological mechanisms that might be implicated in hypersexuality. Neuroimaging can also help provide evidence, if it does exist, of possible brain dysfunction that might be linked to hypersexual behavior. However, claims being made by some individuals that these few neuroimaging studies provide “proof” that sex addiction is a legitimate disorder are premature. Even the authors of these studies do not draw such conclusions!
…we have a long path ahead requiring substantially more rigorous scientific research to help us understand hypersexual behavior and whether it should be classified as a disorder.-Rory C. Reid
Complicating matters, in some cases conflicting results from data on patients with hypersexual problems have emerged. For example, neuropsychological data exploring executive deficits (e.g., problems with processing information in the frontal lobe of the brain) among hypersexual men has yielded mixed findings where self-reported executive deficits were noted but failed to be supported when executive dysfunctions were objectively tested.  The reality is we have a long path ahead requiring substantially more rigorous scientific research to help us understand hypersexual behavior and whether it should be classified as a disorder.
Sex Addiction Causes Damage, How Can it Not be a Disorder?
Although significant consequences such as personal distress or impairment are common denominators associated with many DSM disorders and also occur with hypersexuality, such negative consequences are insufficient to classify hypersexuality as a psychiatric disorder or what people commonly call mental illness. One must consider the vast array of issues in life resulting in harm or significant negative outcomes that do not constitute a mental illness.
For example, negative aspects of perfectionism have been shown to interfere with relationships, contribute to job loss, predict earlier mortality, and have been associated with diagnosable psychiatric disorders such as eating disorders and depression. Perfectionism, however, has been characterized as a personality trait not a psychiatric disorder.
Nevertheless, treatment approaches have been developed for reducing the distress associated with negative aspects of perfectionism. Thus, perfectionism is an issue that attracts serious attention of researchers and clinicians, can result in negative consequences and personal distress, has been studied extensively by the scientific community, and is the focus of treatment by health care professionals — all of this without classifying perfectionism as a disease or psychiatric disorder.
…the great work that has been done in the field of perfectionism can offer a template for those working with hypersexual behavior.-Rory C. Reid
Using this analogy, more research is needed to understand whether hypersexuality constitutes a problem in living, internal conflict around sexual values, a culturally-bound construct, a personality trait, or if this phenomenon meets the more stringent standard required for a psychiatric disorder. Regardless, the great work that has been done in the field of perfectionism can offer a template for those working with hypersexual behavior.
Where Do We Go from Here?
Collectively, the scientific evidence for hypersexual behavior to be classified as a psychiatric disorder is incomplete at the present time. While “sex addiction” is not a sanctioned disorder by the American Psychiatric Association, patients should be told that hypersexual behavior frequently co-occurs with other mental disorders and be reassured that their problems can be the focus of treatment, with the caveat that treatment specifically focused on hypersexuality may not be covered by insurance providers.
Whether or not the HD proposal will end up in subsequent updates to the DSM has yet to be determined. Health care providers should understand there is no current gold-standard of care for treating hypersexuality and current outcome studies have significant methodological limitations.  Nevertheless, mental health professionals, researchers, and scientists, should collaborate when possible to find ways to help alleviate the suffering and distress encountered by those experiencing hypersexual behavior.
 Reid, R. C., Carpenter, B. N., Hook, J. N., Garos, S., Manning, J. C., Gilliland, R., Cooper, E. B., McKittrick, H., Davtian, M., & Fong, T. (2012) Report of findings in a DSM-5 Field Trial for Hypersexual Disorder. Journal of Sexual Medicine, 9(11), 2868-2877.
 Kafka, M. P. (2014). What happened to hypersexual disorder? Archives of Sexual Behavior, 43(7), 1259-1261.
 Kor, A., Fogel, Y. A., Reid, R. C., & Potenza, M. N. (2013). Should hypersexual disorder be classified as an addiction? Journal of Sexual Addiction & Compulsivity, 20(1-2), 27-47.
 Miner, M. H., Raymon, N, Mueller, B. A., Lloyd, M., Lim, K. L. (2009). Preliminary investigation of the impulsive and neuroanatomical characteristics of compulsive sexual behavior. Psychiatry Research, 174, 146-151.
 Reid, R. C., Garos, S., Carpenter, B. N., & Coleman, E. (2011). A surprising finding related to executive control in a patient sample of hypersexual men. Journal of Sexual Medicine, 8(8), 2227–2236.
 Hook, J. N., Reid, R. C., Penberthy, J. K., Davis, D. E., & Jennings, D. J. (2014). Methodological review of treatments for non-paraphilic hypersexual behavior. Journal of Sex & Marital Therapy, 40(4), 294-308.