The Medical and Dental Defence Union of Scotland (MDDUS) said doctors were increasingly receiving requests from patients to prescribe medication recommended by overseas doctors. Often, the drugs were unlicensed in the UK or had differing dosage.
The organisation warned doctors they must be able to explain and justify their prescribing.
Many reported cases involved fertility treatment, which is often cheaper abroad. On return to the UK, patients had asked GPs to prescribe medicines that are usually provided by specialist centres.
Dr Mary Peddie, MDDUS medical advisor, said: 'If you do not consider that you have the appropriate knowledge and experience to prescribe a particular medicine, you do not have to do so. But you should explain your reasons for declining and explain other available options, including the option to seek a second opinion.'