Nomophobia occurs in situations when an individual experiences anxiety due to the fear of not having access to a mobile phone. The "over-connection syndrome" occurs when mobile phone use reduces the amount of face-to-face interactions thereby interfering significantly with an individual’s social and family interactions. The term "techno-stress" is another way to describe an individual who avoids face-to-face interactions by engaging in isolation including psychological mood disorders such as depression.

Anxiety is provoked by several factors, such as the loss of a mobile phone, loss of reception, and a dead mobile phone battery. Some clinical characteristics of nomophobia include using the device impulsively, as a protection from social communication, or as a transitional object. Observed behaviors include having one or more devices with access to internet, always carrying a charger, and experiencing feelings of anxiety when thinking about losing the mobile.

Other clinical characteristics of nomophobia are a considerably decreased number of face-to-face interactions with humans, replaced by a growing preference for communication through technological interfaces, keeping the device in reach when sleeping and never turned off, and looking at the phone screen frequently to avoid missing any message, phone call, or notification (also called ringxiety). Nomophobia can also lead to an increase of debt due to the excessive use of data and the different devices the person can have. Nomophobia may also lead to physical issues such as sore elbows, hands, and necks due to repetitive use.

Irrational reactions and extreme reactions due to anxiety and stress may be experienced by the individual in public settings where mobile phone use is restricted, such as in airports, academic institutions, hospitals and work. Overusing a mobile phone for day-to-day activities such as purchasing items can cause the individual financial problems. Signs of distress and depression occur when the individual does not receive any contact through a mobile phone. Attachment signs of a mobile phone also include the urge to sleep with a mobile phone. The ability to communicate through a mobile phone gives the individual peace of mind and security.

Nomophobia may act as a proxy to other disorders. Those suffering from an underlying social disorder are likely to experience nervousness, anxiety, anguish, perspiration, and trembling when separated or unable to use their digital devices due to low battery, out of service area, no connection, etc. Such people will often insist on keeping their devices on hand at all times, typically returning to their homes to retrieve forgotten cell phones.

Nomophobic behavior may reinforce social anxiety tendencies and dependency on using virtual and digital communications as a method of reducing stress generated by social anxiety and social phobia. Those suffering from panic disorders may also show nomophobic behavior, however, they will probably report feelings of rejection, loneliness, insecurity, and low self-esteem in regard to their cell phones, especially when times with little to no contact (few incoming calls and messages). Those with panic disorder will probably feel significantly more anxious and depressed with their cellphone use. Despite this, those suffering from panic disorder were significantly less likely to place voice calls.

With the changes of technologies, new challenges are coming up on a daily basis. New kinds of phobias have emerged (the so-called techno-phobias). Since the first mobile phone was introduced to the consumer market in 1983, these devices have become significantly mainstream in the majority of societies.

Shambare, Rugimbana & Zhowa (2012) claimed that cell phones are "possibly the biggest non-drug addiction of the 21st century", and that colleges students may spend up to nine hours every day on their phones, which can lead to dependence on such technologies as a driver of modern life and an example of "a paradox of technology". that is both freeing and enslaving.

A survey conducted by SecurEnvoy showed that young adults and adolescents are more likely to suffer from nomophobia. The same survey reported that 77% of the teens reported anxiety and worries when they were without their mobile phones, followed by the 25-34 age group and people over 55 years old. Some psychological predictors to look for in a person who might be suffering of this phobia are "self negative views, younger age, low esteem and self-efficacy, high extroversion or introversion, impulsiveness and sense of urgency and sensation seeking".

Among students, frequent cell phone usage has been correlated with decreases in grade point average (GPA) and increased anxiety that negatively impacts self-reported life satisfaction (well-being and happiness) in comparison to students with less frequent usage. GPA decreases may be due to the over-use of cell phone or computer usage consuming time and focus during studying, attending class, working on assignments, and the distraction of cell phones during class. Over-usage of cell phones may increase anxiety due to the pressure to be continually connected to social networks and could rob chances of perceived solitude, relieving daily stress, that has been linked as a component of well-being.