OBJECTIVE: To investigate whether advice from a person's social network triggers contact with the general practitioner (GP).

DESIGN: Case-crossover design comparing the frequency of advice given to seek medical attention in the period before contact with a GP and the frequency in matching control time periods for the same individual.

SETTING: Twenty-one Danish GPs working in single-handed practices.

SUBJECTS: 322 patients, aged between 18 and 91 years, were interviewed by telephone after an unscheduled visit to their GP; 148 were interviewed again 3-6 months later.

MAIN OUTCOME AND MEASURES: The odds of individuals consulting their GP after receiving advice from network members in the period before they contacted their GP compared with the odds of those consulting their GP in the control period(s).

RESULTS: Being advised by others to seek medical attention increased the likelihood of seeking primary health care approximately fivefold--single men received advice significantly less frequently (7%) than women (18%) and cohabiting men (32%).

CONCLUSION: Advice from other social network members to seek medical attention is a frequent and influential cue prompting individuals to contact their GP.