Drinking alcohol in the evening: is it safe to drive the next morning?

A 38-year-old Hanoi resident, Truong, asks: "If I drink alcohol at 7 PM and then consume a lot of water to flush it out, will my blood alcohol content be zero by 7 AM, making it safe to drive?"

Reply:

It is challenging to determine precisely if your body has fully eliminated alcohol, even after many hours. For accurate results and to ensure safety before driving, a breathalyzer is the most reliable tool.

Alcohol elimination rates vary significantly among individuals, influenced by age, weight, health conditions, and how alcohol is consumed. According to the World Health Organization (WHO), one unit of pure ethanol, equivalent to 10 grams of alcohol, is typically processed by a healthy adult liver in about one hour. This unit corresponds to approximately 200 ml of beer, 75 ml of wine (one glass), or 25 ml of spirits (one shot). While the liver handles 85-90% of alcohol, the remaining 10-15% is expelled through respiration, skin, and sweat.

Factors like existing liver conditions or metabolic disorders can slow down alcohol processing. Similarly, consuming alcohol on a full stomach can delay absorption and, consequently, elimination. Therefore, relying solely on time passed or drinking water is not sufficient to guarantee a zero blood alcohol level. Ensuring complete alcohol elimination is crucial not only for road safety but also to avoid legal penalties.

Regarding the question of whether alcohol consumed at 7 PM would be gone by 7 AM the next day, it is impossible to give a definitive "yes" or "no" without knowing specific details of consumption and individual physiology. While some online tools allow you to estimate blood alcohol content and elimination time by inputting specific data, these methods can have inaccuracies. Ultimately, a breathalyzer provides the most dependable assessment.