She has had a breakthrough with several such candidates, which she hopes could lead to earlier diagnosis and, eventually, a preventive medication.

I have been taking preventive medication for acid reflux.

Preventive medication has to be taken on a daily basis, usually for a few weeks, before the effectiveness can be determined.

Common forms of preventive medication for sheep are vaccinations and treatments for parasites.

These rebound headaches can actually make the body less responsive to preventive medication.