The objective of this study was to investigate the effects of rumen-protected capsicum (RPC; Nexulin, Pancosma, Switzerland) alone or a combination with an artificial sweetener (Sucram, Pancosma) on productivity and fat mobilization in early lactation dairy cows. The study involved 15 primi- and 30 multiparous Holstein cows in a randomized complete block design experiment. Cows were blocked based on parity, predicted calving date, and predicted milk yield. Treatments were (15 cows/treatment): (1) control (no additive), (2) 100 mg/cow/d of RPC (RPC), and (3) RPC plus Sucram at 2 g/cow/d (RPCSUC). Three wks before calving, RPC and RPCSUC cows received 100 mg/cow/d RPC. Production data were collected for 8 wks after calving. Dry matter intake (DMI) was restricted from d 8 to 11 post-calving to 70% of prior DMI to experimentally induce subclinical ketosis. Blood samples were collected on d 10 and 11 during feed restriction and analyzed for concentrations of nonesterified fatty acids (NEFA), BHB, and glucose. Data were analyzed using the MIXED procedure of SAS as repeated measures (where applicable); production data were analyzed by week. Treatment did not affect DMI (P ≥ 0.24; average of 21.6 kg/d; SEM = 1.33). Compared with the control alone, milk yield tended to be increased (P = 0.06) by RPC (45.5 vs 42.3 kg/d) in wk 3 (i.e., post-feed restriction), and was or tended to be increased for wk 4 (49.4 vs 44.6 kg/d; P = 0.02) and 5 (50.5 vs 46.8 kg/d; P = 0.11). Feed efficiency also tended to be greater (P = 0.08) for RPC vs the control (2.21 vs 1.99 kg/kg, respectively) in wk 3. Milk composition, body weight change, and body condition score were not affected (P ≥ 0.16) by treatment. Treatment had no effect (P ≥ 0.64) on blood NEFA, BHB, and glucose. In this experiment, dietary supplementation of RPC, but not artificial sweetener, appeared to increase milk production and feed efficiency in dairy cows following feed restriction to induce sub-clinical ketosis and had no effect on fat mobilization.