COX-2 inhibitor can prevent "religious headache" during fast

Every year, millions of observant Jews fast on their holiest day, Yom Kippur, and millions of Muslims fast for the month of Ramadan. And every year, as many as 40% of those who fast develop serious headaches.

Yom Kippur headache is a well documented phenomenon but the causes are unclear, but doctors have suspected withdrawal from caffeine, nicotine, oversleeping, and dehydration.

About 36% of subjects who took COX-2 inhibitor etoricoxib (related to Vioxx) developed headaches, compared to about 68% who took placebo. Those who took etoricoxib also had less severe headaches, and they had an easier time fasting.

References:
Could Vioxx cousin prevent religious fast headache? WebMD.

Image source: Etoricoxib, Wikipedia, public domain.