Why do you get a headache after drinking?

Alcohol that we drink is essentially ethanol (CH3CH2OH).

In our body, ethanol is metabolized into acetaldehyde by an enzyme called alcohol dehydrogenase (ADH). In turn, the acetaldehyde is also metabolized to acetate by acetaldehyde dehydrogenase (ALDH). These metabolizing enzymes are found in liver. Acetate is used in several biological cycles such as in muscle cells to produce acetyl-CoA etc.

Our headache (and other hangover symptoms) is believed to be caused by this acetaldehyde in our blood. It takes time for our body to metabolize acetaldehyde and this time depends on how much alcohol you drink. Less = shorter^^

In our body's point of view, alcohol is a toxic substance with its toxicity levels closely related to the dosage. Metabolism is a way for our body to breakdown this toxic substance in our system.

Ethanol is a central nervous system depressant and a psychoactive drug so moderate amount of drinking for recreational purposes is very ok!! :)

If you suffer from hangover and headaches after drinking, just wait it out and give your body time to flush the alcohol out. If possible, try not to take analgesic drugs like paracetamol or aspirin to relieve your symptoms as your liver is already busy with metabolizing your alcohol.

Alcohol tends to dehydrate so drink plenty of water and don't skip out on your meals in order to keep your metabolic process active!!