Drinking alcohol can affect many parts of your body, including your kidneys. A little alcohol—one or two drinks now and then—usually has no serious effects. But drinking too much can harm your health. It can also worsen kidney disease.
How does alcohol harm the kidneys?
Your kidneys filter harmful substances from your blood. One of these substances is alcohol. Alcohol can cause changes in the function of the kidneys and make them less able to filter your blood. In addition to filtering blood, your kidneys do many other important jobs. One of these jobs is keeping the right amount of water in your body. Alcohol affects the ability of your kidneys to do this. When alcohol dehydrates (dries out) the body, the drying effect can affect the normal function of cells and organs, including the kidneys.
Too much alcohol can also affect your blood pressure. People who drink too much are more likely to have high blood pressure. And medications for high blood pressure can be affected by alcohol. High blood pressure is a common cause of kidney disease. More than two drinks a day can increase your chance of having high blood pressure.
Chronic drinking can also cause liver disease. This adds to the kidney's job. The rate of blood flow to your kidneys is usually kept at a certain level, so that your kidneys can filter your blood well. Liver disease impairs this important balancing act. In fact, most patients in the United States who have both liver disease and associated kidney dysfunction are alcohol dependent.
How much alcohol is too much?
When experts talk about one drink, they are talking about one 12-ounce bottle of beer, one glass of wine (5 ounces), or one shot (1.5 ounces) of "hard liquor."
Having more than three drinks in a day (or more than seven per week) for women, and more than four drinks in a day (or more than 14 per week) for men, is considered "heavy" drinking. The kidneys of heavy drinkers have to work harder. Heavy drinking on a regular basis has been found to double the risk for kidney disease.
Binge drinking (usually more than four to five drinks within two hours) can raise a person's blood alcohol to dangerous levels. This can cause a sudden drop in kidney function known as "acute kidney injury." When this happens, dialysis is needed until a person's kidney function returns to normal. Acute kidney injury usually goes away in time, but in some cases, it can lead to lasting kidney damage.
Some people should not drink at all. Ask your healthcare provider if it is safe for you to drink, especially if you have a medical condition or take medicines that might be affected by using alcohol. Women, older people, and those with smaller bodies should be especially careful. Of course, pregnant women are advised not to drink alcohol.
What can you do?
Always check with your healthcare provider to make sure it is safe for you to drink alcohol. Even if it is safe, it is important to drink in moderation. A good guideline is: no more than one to two drinks a day for men and one drink a day for women and people over 65.
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© 2014 National Kidney Foundation. All rights reserved. This material does not constitute medical advice. It is intended for informational purposes only. Please consult a physician for specific treatment recommendations.