A single glass of wine remains in the bloodstream for approximately 3 hours. This can vary depending on a few factors such as weight and sex.
The amount of time alcohol stays in the blood stream is dependent on many factors. The main factor is how many units are consumed. A glass of wine has about 3 units while a beer has about 2. It takes an hour for the alcohol in a unit to break down. Any medications being taken can cause the alcohol to break down more slowly. Also, the alcohol usually lasts longer in a smaller person's body.