Abstract. Tuberculosis (TB) and HIV co-infection increases the complexity of therapy because patients receive antituberculosis drugs (OAT) concurrently with antiretroviral therapy (ART) over a long period, thereby increasing the risk of Adverse Drug Reactions (ADR). This study aimed to determine the types and prevalence of potential ADR during therapy in TB-HIV patients. The study used a descriptive observational design with a cross-sectional approach, with data collected retrospectively from electronic medical records at Hospital X for the period 2024–2025, using a total sampling method based on inclusion and exclusion criteria. A total of 75 patients met the criteria, predominantly male (73.33%) and aged 18–59 years (98.67%), with pulmonary tuberculosis as the most com mon diagnosis (38.67%). All patients received first-line Fixed-Dose Combination (FDC) category-1 OAT, while the most commonly used ART regimen was TDF/3TC/EFV (65.33%). Of the 212 recorded ROTD events, the most frequently occurring were gastrointestinal disorders in the form of nausea and vomiting (20.57%), respiratory disorders in the form of cough (12.44%), and skin disorders in the form of itching (8.61%). These findings indicate that gastrointestinal, respiratory, and skin reactions are the most common adverse effects and require regular monitoring throughout combined TB-HIV therapy. Abstrak. Ko-infeksi tuberkulosis (TB) dan HIV meningkatkan kompleksitas terapi karena pasien mendapatkan obat antituberkulosis (OAT) secara bersamaan dengan terapi antiretroviral (ART) dalam jangka waktu panjang, sehingga meningkatkan risiko terjadinya Reaksi Obat Tidak Diinginkan (ROTD). Penelitian ini bertujuan untuk menentukan jenis dan prevalensi potensi ROTD selama terapi pada pasien TB-HIV. Penelitian menggunakan desain observasional deskriptif dengan pendekatan cross sectional, data diambil secara retrospektif melalui e-rekam medis di RS X periode 2024–2025, dengan metode total sampling berdasarkan kriteria inklusi dan eksklusi. Diperoleh 75 pasien yang memenuhi kriteria, didominasi laki-laki (73,33%) dan berusia 18–59 tahun (98,67%), dengan diagnosis terbanyak tuberkulosis paru (38,67%). Seluruh pasien menggunakan OAT Kombinasi Dosis Tetap (KDT) kategori-1, sedangkan regimen ART yang paling banyak digunakan adalah TDF/3TC/EFV (65,33%). Dari 212 kejadian ROTD yang tercatat, yang paling sering muncul adalah gangguan gastrointestinal berupa mual muntah (20,57%), gangguan pernapasan berupa batuk (12,44%), dan gangguan kulit berupa gatal (8,61%). Hasil penelitian ini menunjukkan bahwa reaksi gastrointestinal, pernapasan, dan kulit merupakan efek samping yang paling sering muncul dan perlu dipantau secara berkala selama terapi kombinasi TB-HIV berlangsung.