What is alcohol intolerance?

Alcohol intolerance is an umbrella term for reacting badly to alcohol fast - flushing, a stuffy or runny nose, nausea, headache, racing heart, or worsening asthma within minutes to an hour of even small amounts. The most common cause is genetic: the ALDH2 enzyme variant behind the alcohol flush reaction, frequent in East Asian ancestry, which lets the toxic byproduct acetaldehyde accumulate. The NIAAA notes this reaction is both unpleasant and a genuine cancer-risk warning for people who keep drinking through it. Other mechanisms: some people react to ingredients rather than alcohol itself - histamines in red wine and beer, sulfites, or grains - which looks like allergy: congestion, sneezing, hives. True alcohol allergy exists but is rare. Alcohol also interacts badly with certain medications - metronidazole and some others trigger flushing, vomiting, and racing heart by design. What to do: the reliable fix is avoiding or sharply limiting alcohol, since no pill neutralizes the reaction. Note which drinks trigger it - red wine versus clear spirits - because ingredient reactions can be skirted while genetic intolerance cannot. Sudden new intolerance in someone who used to drink fine deserves a mention to a doctor, since liver changes and new medications sit on the list of causes. Pymander is a free AI doctor, 24/7 by text. Describe your reaction and the drinks involved, and it can help you sort the likely mechanism.