Methylphenidate hydrochloride sustained-release tablets are a first-line medication for treating attention deficit hyperactivity disorder (ADHD). However, appetite loss is one of its most common adverse reactions, with an incidence rate of up to approximately 70%, significantly affecting children's nutritional intake and growth and development. From the perspective of traditional Chinese medicine (TCM) theory, this paper proposes that the primary pathogenesis of appetite loss induced by methylphenidate hydrochloride sustained-release tablets is "drug toxicity damaging the central yang—spleen and stomach deficiency-cold." Based on this, a synergistic treatment approach combining Lizhong Decoction to warm the middle and invigorate the spleen and acupoint catgut embedding to regulate stomach function is proposed. Lizhong Decoction, originating from Zhang Zhongjing's "Treatise on Febrile Diseases, " is a representative formula for spleen and stomach deficiency-cold syndrome in Taiyin disease. Modern research confirms that it can improve gastrointestinal motility by increasing levels of gastrointestinal excitatory hormones such as motilin, substance P, and ghrelin. Acupoint catgut embedding, an extension of acupuncture therapy, regulates the hypothalamic feeding center and gastrointestinal function through continuous stimulation of acupoints such as Zusanli, Zhongwan, and Tianshu, producing a lasting effect on appetite regulation. The combination of internal and external treatments synergistically enhances the effects of warming the middle and invigorating the spleen and regulating the feeding-digestion axis. This paper presents a case study to demonstrate the clinical efficacy of this combined approach in improving appetite loss induced by methylphenidate, providing a reference for clinical practice.