Many homebrewers report that they have gotten a bad headache or hangover after drinking their beer, even if they drank in moderation.
Other than overconsumption, the most likely reason for getting a headache or hangover after drinking homebrew is the presence of fusel alcohols in the beer.
Since alcohol is a diuretic, it also causes your body to remove more fluid than normal, it can easily cause you to become dehydrated, if you aren’t careful, and suffer a major headache as a result.
Since the chemical changes and other activity that takes place through the Ehrlich pathway happens relatively slowly compared to the rest of the fermentation process, it can take quite a while for the fusel alcohols to clear up.
Fusel alcohols contribute an ‘alcoholic’ or ‘boozy’ taste in homebrew and can also add a warming sensation to the taste, aroma, and even inside your stomach. Beers with too much fusel alcohol in them might be referred to as ‘hot’ beers.
– Bring your wort to a quick, rolling boil without a lid whenever possible – Use a yeast starter to ensure that you aren’t underpitching – Keep fermentation temperatures stable throughout – Keep beer in the primary longer
Anecdotally, many homebrewers have said that they were able to reduce the taste and aroma of fusel alcohol by letting their beer sit in the bottle for a longer period of time before drinking it.