After consuming alcohol, the body absorbs it rapidly, leading to a rise in blood alcohol concentration (BAC) [1][2]. According to the National Highway Traffic Safety Administration (NHTSA), alcohol is absorbed into the bloodstream at an average rate of 0.015 to 0.030 grams per deciliter per hour [3]. This absorption rate can vary depending on several factors, such as the amount and type of alcohol consumed, the individual's weight, gender, metabolism, and whether food was consumed along with the alcohol [1][2].

Generally, BAC rises fastest during the first hour after drinking, as the body absorbs alcohol more quickly than it can metabolize it [1][2]. However, it is essential to note that the rate of absorption can be influenced by various factors, and individual experiences may vary.

In summary, alcohol levels typically rise quickly after consumption, with the greatest increase occurring during the first hour. However, the exact rate of increase can vary depending on individual factors and the specific circumstances of alcohol consumption.

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/ALCOHOL>
[2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4112772/>
[3] <https://www.nhtsa.gov/risky-driving/drunk-driving>