Heat stress (HS) negatively affects physiological parameters in dairy cows. Electrolyte supplementation may improve acid-base balance, water intake, and ultimately reduce body temperature. Therefore, study objectives were to determine the effects of a product containing electrolytes, osmolyte, and energetic compounds (EOEC) as re-hydration therapy on body temperature indices in HS lactating Holstein cows. Nineteen multiparous, lactating cows were housed in individual-box stalls and randomly assigned to 1 of 2 dietary treatments: 1) a control diet (n = 9) or 2) a control diet supplemented with 113 g/cow/d of EOEC (n = 10; Bovine BlueLite Pellets; TechMix, LLC, Stewart, MN) top-dressed once daily. The trial consisted of 2 experimental periods (P). During P1 (4 d), cows were fed their respective treatments and housed in thermoneutral conditions for collection of baseline data. During P2 (4 d), HS was artificially induced by using an electric heat blanket (EHB; Thermotex Therapy Systems Ltd. Calgary, Canada). Vaginal temperature (Vt) was measured every 10 min using a data logger (iButton DS1921, Maxim Integrated, San Jose, CA). Overall, the EHB increased rectal temperature (Tr), Vt, skin temperature (Ts), respiration rate (RR), and heart rate (HR) (1.6°C, 1.5°C, 1.7°C, 2-fold, and 11 bpm, respectively; P < 0.01) relative to P1. There were no dietary treatment differences in Tr, Vt, RR, and HR (P = 0.40); however, EOEC-supplemented cows had increased Ts relative to controls (0.64°C; P = 0.04). Compared with P1, the EHB decreased DMI and milk yield (45 and 22%, respectively; P < 0.01), but no differences were observed between dietary treatments. Relative to controls, circulating glucose tended to be increased (5%; P = 0.07) and insulin was increased (1.95 fold; P = 0.01) in EOEC-fed cows. A treatment by day interaction was detected for NEFA levels where EOEC-fed cows tended to have decreased (20%) NEFA levels at the end of P2 compared with controls (P = 0.06). In summary, feeding EOEC altered metabolism and increased Ts but not Tr, Vt, RR, and HR. Increased Ts may suggest that EOEC increased heat dissipation, likely via increased sweating.