The goal of this study was to evaluate, in a commercial herd, the use of isoquinoline alkaloids and carvacrol versus a preventive antibiotic program, such as feed additives, on the performance, carcass traits, and health status of pigs in the growing and finishing phase. There were 576 PIC immunocastrated males and females, at 70 days of age and 28.429 ± 2.302 kg of initial weight used. The experimental design was a 4 × 2 factorial randomized block, with four preventive programs, two sexes, and six repetitions per treatment (the pen with 12 animals of the same sex was the replicate). The treatments were T1 (positive control program with antibiotic shocks at preventive level), T2 (negative control with the absence of antibiotics as a growth promoter or as preventive), T3 (isoquinoline alkaloids at 100 to 150 g ton-1), T4 (isoquinoline alkaloids at 90 g ton-1 + carvacrol essential oil at 1 kg ton-1). T1 and T3 presented higher daily feed intakes, followed by T2, and T4 showed the worst feed consumption (P < 0.05). T1 showed higher daily weight gain compared to T4 (P < 0.05), without differences between T2 and T3. T2 showed better feed conversion than T1 and T3, but it was similar to T4. There were no effects of the treatments on the carcass traits. Intestinal crypt hyperplasia and crypt abscesses (lesions caused by Lawsonia intracellularis) were significantly higher for T2 and T3 compared to T1, which was similar to T4. T2 presented the highest carcass condemnation at slaughter (7%), differing (P < 0.05) from T1, T3, and T4 (1, 2, and 3%, respectively). Isoquinoline alkaloids are an alternative for antibiotic-free diets for pigs in the growing and finishing phase, preserving the performance and carcass indices and minimizing sanitary carcass condemnations at the slaughterhouse.