At present, mourners can feel sad for two months before being told they have a mental disorder, Professor Dale Larson said. Decades ago, a diagnosis could be made after a year.
In a keynote address at an Australian Psychological Society conference in Melbourne on Saturday, Prof Larson will express his anger about the American Psychiatric Association's new diagnostic manual, DSM 5, which is used in many countries including Australia and New Zealand.
The manual allows a diagnosis of depression after two weeks of grieving, News.com.au reported.
According to Prof Larson, the manual undermines the legitimate feelings of the mourner and the help available from family, support groups, clerics and professional counsellors.
"We are essentially labelling grief a disorder. Now it becomes a target for drug development," Larson said.
Prof Larson, head of Counselling Psychology at Santa Clara University in the US, is concerned GPs will be dishing out prescriptions for anti-depressants.
"Almost all bereaved people believe they are depressed. But grief is a normal healing process and it resolves itself in most cases," Larson said.
"Bereavement-related depression is different from other kinds of depression."
"Medication, not psychotherapy, will be the major treatment because most people see their GP when they have an issue," he added.
He acknowledged support in Australia might be more focused on the needs of the mourner, who could take advantage of a Medicare benefit and consult a psychologist.
He said the focus should be on helping the mourner figure out grief's questions like, "What's happening to me and how long will it last?"