This case report examines the impact of a single session of functional neurology on a 35-year-old female patient diagnosed with lactose intolerance. The patient presented with severe gastrointestinal symptoms, including frequent diarrhea, bloating, and vomiting upon dairy consumption. The intervention aimed to reset dysfunctional neurological programs believed to contribute to her condition. The study utilized a standardized lactose intolerance breath test to measure the hydrogen and methane levels at various intervals before and after treatment. Post-treatment results showed symptomatic relief with the patient reporting normalized bowel movements and the absence of previous symptoms. Despite these improvements, the biochemical markers at higher time points (150 and 175 min) post-treatment remained similar to the pre-treatment values, indicating persistent lactose malabsorption and highlighting the variability of hydrogen measurements. This case report suggests that a single session of functional neurology can significantly alleviate the symptoms of lactose intolerance. However, the preliminary nature of these results underscores the need for further research involving larger sample sizes and long-term follow-up to fully understand the treatment’s efficacy and underlying mechanisms.