Agni and Kostha are fundamental concepts in Ayurveda that influence physiological balance, disease development, and treatment effects. Agni manages digestion, metabolism, and the transformation of tissues. Kostha indicates bowel habits and the functioning of the gastrointestinal tract. Assessing both factors is essential when choosing between Samana (palliative therapy) and Shodhana (purificatory therapy). Individual differences in Agni—such as Vishama, Tikshna, Manda, and Sama—along with Kostha types—Krura, Madhyama, and Mridu—inform the strength, dosage, and order of treatments. A poor assessment can reduce treatment effectiveness, resulting in incomplete detoxification or worsened dosha conditions. Classical texts like Charaka Samhita and Ashtanga Hridaya highlight that the success of therapies such as Deepana-Pachana, Snehapana, Swedana, Vamana, Virechana, and Basti relies significantly on the evaluation of Agni and Kostha. This article examines the physiological importance of these factors, discusses their influence on selecting Samana and Shodhana Chikitsa, and emphasizes how personalized therapy leads to safer and more effective results. By combining traditional knowledge with modern clinical views, the article highlights the need for individualized Ayurvedic care. Understanding Agni and Kostha gives a solid foundation for choosing treatment options, optimizing detoxification, improving metabolic functions, and avoiding treatment-related issues. This review concludes that a thorough evaluation of Agni and Kostha is central to evidence-based Panchakarma practice and supports long-term health recovery.