According to most experts with a serious interest in the topic, most morning-after medications and emergency measures are no more than placebos, banking heavily on the power of belief and a hefty dose of wishful thinking. The only real cure for a hangover is sobriety. That's sensible enough advice, but probably not for everyone. Still, there are precautions that will help check the odds of a hangover. The safest bet of all is to practice moderation when drinking.
Moderation is healthy and painless.
Drink enjoyably, but as part of a social event, not the goal. That means not drinking to escape problems and not drinking to get drunk. That's what it doesn't mean. What it does mean is teaching yourself to view alcohol with the healthy caution it deserves. Food slows the rate at which alcohol is absorbed, lowering peak blood alcohol levels.