Alcohol can trigger a headache immediately or soon after it is consumed or the next morning.   Some people develop a headache only from a particular type of alcohol, such as red wine, rum, or beer, while others cannot drink any form of alcohol without getting a headache.  It seems that vodka is least likely to cause a headache, because it is possible that it is not alcohol that is causing headaches, but rather preservatives, such as sulfites, fermentation products, and natural colors.  Some people are exquisitely sensitive – a small sip of wine can trigger a headache within minutes, and some can drink two glasses of wine without a headache, while the third glass will always result in a headache.  If you’ve found a medicine that works for your headaches, have it handy since the sooner you take it the better it will work.  However, check with your doctor to see if your medicine can be taken with alcohol (none of them should be mixed with alcohol, but some are more dangerous than other).  Headaches that occur the day after drinking are usually due to overindulgence and are thought to be in part due to dehydration and in part due to magnesium depletion by alcohol.