Chronic heavy alcohol use and alcohol withdrawal are known to diffusely damage white matter (WM), but it has remained rather unclear whether the damage sustained during a single withdrawal event is functionally relevant and whether WM damage also occurs during or after single episodes of heavy drinking. We therefore set out to investigate the effects of acute alcohol intoxication, alcohol hangover and (post)acute alcohol withdrawal on axonal injury (assessed via serum neurofilament light chain/NFL) and potentially associated cognitive-behavioural functioning (as assessed with the CANTAB test battery) in three separate studies. Acute intoxication and hangover effects were studied in healthy young men who underwent a standardized intoxication procedure aiming at an intoxication level of approx. 1.2‰ in two separate randomized experimental crossover studies. (Post)acute withdrawal effects were longitudinally observed in withdrawal patients during a 21-day inpatient qualified detoxification treatment. There was no significant effect of alcohol intoxication (n = 51) or alcohol hangover (n = 80) on NFL levels. In contrast, withdrawal patients (n = 31) revealed significant changes of NFL levels over the course of inpatient treatment; most prominently an increase from the first day of admission to the peak of withdrawal symptoms and a decrease from there to the day of hospital discharge. Higher NFL levels of withdrawal patients were associated with slower motor responses and lower risk taking/delay aversion in gambling, as assessed with the CANTAB test battery. In conclusion, the functionally relevant increase in axonal injury despite gold-standard inpatient treatment for alcohol withdrawal necessitates further investigation.