The pupil, whose identity has not been made public, is said to have sent the explicit image from his bedroom while “flirting” with a girl of the same age, who then shared it with others.
He was later told the incident was added to his file on the police’s national database after the image came to the attention of a police officer based at the school, in the north of England.
The file remains active for a minimum of 10 years, meaning potential employers conducting an advanced Criminal Records Bureau check could be told.
The incident, deemed an example of “sexting”, has been recorded as a crime of making and distributing an indecent image, the boy’s mother told BBC Radio 4’s Today programme, even though he was not arrested or charged.
The boy said he was “embarrassed” by the incident and now spends lunchtimes in the library to avoid being teased by classmates who have seen the image.
He said: “I shouldn’t have done it. It’s just annoying really, something that I did when I was 14 could reflect badly in future.”
It is not clear whether a similar police file was created for the girl who received and shared the image, or what action was taken against her.
People who have found indecent or explicit images of themselves shared or posted on the internet have routinely been treated as victims rather than aggressors since the introduction of a revenge porn law in April.
The boy’s mother told Today: “I think at best he was naive and at worst he was just a teenager.
“It (sending the image) is referred to as sexting, and apparently it happens all the time. It is just how teenagers flirt these days.”
The National Crime Agency (NCA) launched a campaign in June after being inundated with reports of sexting.
The NCA’s centre for tackling abuse, Ceop Command, said on average it received one report a day of a child protection issue linked to the craze.
In some instances youngsters have been targeted by strangers who attempted to blackmail them over images they had been tricked into taking, the NCA said.
Other cases have involved recipients of private messages forwarding them to others or a user posting a picture of themselves on a website or social media with low privacy settings.
Last year, Nottinghamshire Police were forced to issue a warning to children in response to daily reports of sexting.
In a letter to schools, Detective Inspector Martin Hillier said sending explicit images could result in court action or see a child forced to register as a sex offender.
In one recent case cited in the letter, a teenage girl who sent a topless picture of herself to her boyfriend was investigated after being deemed to have distributed an indecent image of a child. The girl’s boyfriend, who forwarded the image to friends after they split up, is reported to have received a caution.
Responding to the incident of the 14-year-old boy, the Home Office said it was “the responsibility of individual police forces” to accurately record crimes in accordance with strict counting rules.