Trial of Etoricoxib (Arcoxia) Taken Prophylactically to Prevent Ramadan Headache

The investigators intend to study whether the use of the pain medication etoricoxib (Arcoxia) taken just before the Ramadan fast will prevent or lessen headache that some people get while fasting. The investigators hypothesize that etoricoxib will reduce the number of people getting headache, more than placebo. The investigators will do this by giving participants in the study either real medication or placebo (sugar pill) and comparing the results. The investigators will study this over two weeks. The first week one group will get the medicine and the other the placebo. The second the groups will switch. Neither the subjects nor the investigators will know who is in which group.