You should visit your GP in the following circumstances:
You are experiencing an allergic reaction to doxycycline, such as skin irritation or diarrhoea
You have missed multiple doses
Your symptoms are persisting after the treatment course
You have had sexual contact with someone during treatment or within the 7-day period after having completed treatment
There is a possibility you may be pregnant
You are experiencing any unusual side-effects such as difficulty breathing, fever, swollen glands.