This is a randomized, double-blinded, placebo-controlled clinical trial to determine the efficacy and safety of a Chinese herbal medicine (Shenlingcao oral liquid) for treating long COVID associated fatigue. Our target population is adults (18-65 years old) with a COVID-19 infection history and have moderate to severe fatigue symptom at least 4 weeks after infection. The total sample size is 152. All participants will be randomly attributed to treatment group or placebo group in 1:1 ratio. The treatment duration is 4-week, and the follow-up period is also 4 weeks. Shenlingcao oral solution has been registered and marketed in mainland China, it is a safe product and pervious studies suggested it has anti-fatigue function. The primary efficacy outcome is the change of scores of Chalder fatigue scale (0-33 points) after 4-week treatment. The primary safety outcome is the number of adverse events. This study will be conducted in Hong Kong Baptist University Mr. \& Mrs. Chan Hon Yin Chinese Medicine Specialty Clinic and Good Clinical Practice Centre.
