Tannins give the colour to your darker beersSome of the worst hangovers I`ve ever had, have come from " red / reddish " beers.
It`s deffo some kind of additive to get the colour that causes the damage.
"Congeners are associated with more severe hangovers. Congeners are chemical by-products of the fermentation process that gives alcoholic drinks their distinctive flavours. Some common congeners include methanol, tannins and acetaldehyde.
Congeners are found in higher concentrations in darker drinks, such as bourbon, whiskey and red wine.
Clear spirits, such as vodka and gin, have comparatively lower concentrations of congeners. In fact, vodka has almost no congeners at all."