BackgroundInfections of Coronavirus Disease-2019 (COVID-19) can cause long-term effects known as long COVID. This pilot study aimed to evaluate the feasibility of a clinical study as well as the efficacy and safety of traditional East Asian herbal medicines in alleviating fatigue and cognitive dysfunction in patients with long COVID. MethodsThis prospective pilot study investigated the use of three types of herbal medicines, Bojungikgi-tang (BIT), Kyungok-go (KOG), and Cheonwangbosim-dan (CBD), for a 12-week period as potential treatments for fatigue and cognitive dysfunction in patients with long COVID. Forty-five patients with long COVID were recruited, and one of three drugs was given based on the patient's symptoms and pattern identification. The effect of herbal medications on fatigue and cognitive function outcomes was assessed over a 36-week period, with patient adherence closely monitored. ResultsAfter 12 weeks of herbal drug administration, fatigue symptoms improved significantly across all groups, with treatment success rates of 80 %, 53.33 %, and 46.67 % in the BIT, KOG, and CBD groups, respectively. However, cognitive dysfunction symptoms showed less improvement, with treatment success rates of 40 %, 46.67 %, and 13.33 % in the BIT, KOG, and CBD groups, respectively. All adverse events reported were mild and unrelated to the medication. The study design was found to be feasible with high medication adherence. ConclusionsThis study demonstrated the feasibility of conducting a clinical trial with three herbal medicines to treat long COVID symptoms like fatigue and cognitive dysfunction.