Experiencing unpleasant reactions after consuming alcohol can be confusing. Many describe this as their body “rejecting” alcohol, a reaction ranging from mild discomfort to severe physical responses. Understanding these reasons clarifies what is happening.
What “Rejecting Alcohol” Means
When people describe their body “rejecting” alcohol, they often refer to alcohol intolerance or, less commonly, an alcohol allergy. Alcohol intolerance is a metabolic disorder where the body cannot efficiently process alcohol. Symptoms appear immediately or shortly after drinking and can include facial redness or flushing, a rapid heartbeat, nausea, vomiting, headaches, a stuffy or runny nose, low blood pressure, hives, or worsening asthma symptoms.
In contrast, a true alcohol allergy involves an immune system response, which is far less common than intolerance. With an allergy, the immune system mistakenly identifies alcohol or an ingredient in the drink as a threat. Symptoms can include itchy skin, hives, swelling of the face, throat, and difficulty breathing. While both conditions can cause nausea, distinct flushing of the skin on the face, neck, and chest is a hallmark symptom of alcohol intolerance.
Why Your Body Reacts to Alcohol
The primary reason for alcohol intolerance is a genetic predisposition, specifically a deficiency in the enzyme aldehyde dehydrogenase 2 (ALDH2). This enzyme breaks down acetaldehyde, a toxic byproduct produced when the liver metabolizes alcohol. If ALDH2 is inactive or less active, acetaldehyde accumulates, leading to characteristic intolerance symptoms. This genetic variation is more prevalent in individuals of East Asian descent, affecting about 36% of this population.
Alcohol intolerance can also be acquired due to various factors, including certain medications that interfere with alcohol metabolism. Existing health conditions, such as asthma or Hodgkin’s lymphoma, can also be associated with increased alcohol sensitivity. For a true alcohol allergy, the immune system overreacts to specific ingredients in alcoholic beverages, rather than the alcohol itself. Common culprits include grains like wheat, barley, or rye, sulfites used as preservatives, yeast, or histamines that are byproducts of fermentation, particularly in red wine.
Next Steps and Medical Guidance
If you experience adverse reactions after drinking alcohol, observe your symptoms and note which beverages trigger them. Avoiding these alcoholic beverages is the most direct way to prevent symptoms. For minor reactions, over-the-counter antihistamines might offer relief from itching or hives.
Seeking medical advice is recommended for an accurate diagnosis and personalized recommendations. A doctor can determine if your symptoms are due to alcohol intolerance, an alcohol allergy, or another underlying condition. It is important to seek immediate medical attention if you experience severe symptoms such as difficulty breathing, swelling of the face or throat, a weak pulse, or signs of anaphylaxis, as these can be life-threatening.