Ok, let's start of simple.
Alcohol is a duiretic
Duiretics leach b vitamins
Alcohol has more calories than any other macronutrient beside fat.
The body burns alcohol calories in priority to any other calorie.
Alcohol depletes omega 3 fatty acids that the brain uses similar to glycogen, as energy.
So, dehydration. Small issue easily counteracted by fluids. Duiretics leech potassium and sodium causing lethargy, so use a liquid especially high in potassium. Supplement b vitamins too if possible.
The brain functions optimally on omega 3 fatty acids. When depleted, it causes inflammation in the brain sheath and Brian, ie creating a headache. So replenish with fat, optimally omega 3's.
Pedialyte is a good option but is lesser than saline, but who the fuck wants to go to a hospital because of a hangover? Drink Pedialyte and kill 3 birds with one stone.
Pharmaceutically these will help quickly and efficiently for symptoms.
Benzos, almost instant relief of symptoms
Opiates, relief of symptoms within 20-60 minutes.(if coupled with acetaminophen, it won't kill your liver unless you have a pre existing liver disease or condition (and you'de likely be aware of that condition already. If you are, avoid acetaminophen)
Cannabis, variables are too many to name but does work well.
All these other bro science suggestions may have merit to some extent, but it's because they
1)replenish fluids lost
2)replenish sodium and or potassium lost
3)replenish fat lost
4)any combination of the above
Obviously the best solution is to obstain from alcohol entirely, or limit alcohol consumption to low/moderate levels.
Other drugs may help as well, just not as well as the ones I mentioned previously.
Some of the posts in this thread should be in a peer reviewed study on pubmed of how alcohol contributes to minor brain damage/trauma