Doxycycline is a member of the ‘tetracycline’ family of antibiotics (tetracycline literally meaning “four rings” based on its chemical structure).

Doxycycline is a good example of what we call a ‘trade off’ — it has some quite severe side effects (headaches, vomiting) but doctors may decide that this is a risk worth taking to be able to treat some nasty and rare infections.

Doxycycline can also have a bad effect on growing teeth, so doxycycline is never given to children under the age of 12, or to pregnant women.