Mild eccentrics, oddball romantics and the lonely, shy and sad could find themselves diagnosed with a mental disorder if proposals to add new conditions to the world's most widely used psychiatric bible go ahead, experts have warned.

A major revision of the the 1994 Diagnostic and Statistical Manual of Mental Disorders, whose fifth edition is due for publication next year, threatens to extend psychiatric diagnoses to millions of people currently regarded as normal, they say. Among the diagnostic labels are "oppositional defiance disorder" for challenging adolescents, "gambling disorder" for those compelled to have a flutter, and "hypersexual disorder" for those who think about sex at least once every 20 minutes. People crippled by shyness or suffering from loneliness could be diagnosed with "dysthymia", defined as "feeling depressed for most of the day".

More worrying, according to some experts, are attempts to redefine crimes as illnesses, such as "paraphilic coercive disorder", applied to men engaged in sexual relationships involving the use of force. They are more commonly known as rapists.

The revised DSM 5, which is in draft form and subject to review, is produced and used in the US but its influence extends to Europe and beyond. Critics fear it could increase the numbers diagnosed with mental illness and treated with powerful drugs when their problems should be addressed by social, educational or political initiatives.

More than 11,000 mental health researchers and experts have called for the draft version of the manual to be abandoned and the review rethought.

Peter Kinderman, professor of clinical psychology at the University of Liverpool, said that in addition to pathologising behaviour that would otherwise be counted as a crime, such as rape, it also pathologised behaviour that did not cause harm to others even though it might be regarded as eccentric, such as dressing up in rubber. "Many people have huge concerns that if a person's sexual history involves repeated episodes of coercion and that is regarded as an illness it gives people an excuse for their disorder," he said.

But other behaviours, such as spending hours on the internet, could be regarded as "making life more interesting and fun". "Many people who are shy, bereaved, eccentric, or have unconventional romantic lives will suddenly find themselves labelled as 'mentally ill'," he said. "This isn't valid, isn't true, isn't humane. And it won't help decide what help a person needs."

Nick Craddock, professor of psychiatry at the University of Liverpool, said the expansionist tendencies of the manual were pulling in more aspects of behaviour and cognition. "That means medicalising normal human behaviour," he said. "It risks labelling people who are otherwise normal."

Psychiatric Bible: New disorders

Gambling disorder Preoccupied with gambling, needing increasing amounts of money for the same level of excitement.

Attenuated psychosis syndrome Delusions, hallucinations, mildly disorganised speech at least once a week.

Hypersexual disorder Recurrent and intense sexual fantasies and urges over at least six months which are unsuccessfully controlled.

Dysthymia A low, dark, or sad mood on most days for at least two years in adults or one year in children.