Television, radio and press activity will alert people to the early signs and symptoms of bowel cancer.
It will run in the East of England and the South West for seven weeks ahead of an expected national rollout.
The £1.75m campaign, created by M&C Saatchi, features real GPs encouraging patients to talk to them about changes in their excrement.
It is part of a £9m fund the Government has handed to local health authorities to build awareness and fund early diagnosis initiatives for breast, bowel and lung cancers.
The campaign was green-lit by the Cabinet Office despite a freeze on marketing spend because it is hoped that it will deliver “measurable benefits relating directly to immediate public health and safety”.