Intravenous Fluids as a Heat Stroke Treatment

Intravenous (IV) infusion of cold fluids is often considered a heat stroke treatment, particularly during transport. But what does the evidence say about its efficacy?

In short, the evidence supports the principle of "cool first, transport second". Given the critical 30-minute window to reduce an exertional heat stroke (EHS) victim's core temperature below 39ºC (~102ºF), powerful cooling modes are required. According to the highly cited systematic review by McDermott et al. (2009), a cooling rate of 0.78 - 1.55ºC per 10 minutes is considered acceptable, and >1.55ºC per 10 minutes is ideal in this regard. Hence, cooling of 0.78ºC per 10 minutes is considered the minimum threshold of acceptable cooling for EHS, and the standard that IV infusion can be compared to.

The three studies summarised in Table 1 reveal modest core temperature cooling rates with IV infusion. These rates were either at the low end of the acceptable range or deemed unacceptable. For instance, infusing fluids at 4ºC versus 22ºC (66mL/min) improved the cooling rate by 14.3% (0.72ºC versus 0.63ºC per 10 minutes), but both options fell within the unacceptable range (Morrison et al., 2018). Sinclair et al. (2009) marginally achieved an acceptable cooling rate for EHS, but required an infusion rate of 84mL/min). While higher pre-treatment core temperatures may improve reported cooling rates (Brearley et al., 2023), cold IV infusion appears inadequate as a stand-alone or primary treatment for EHS, even when infusing 2L of fluid.

Table 1. Summary of three studies assessing intravenous infusion to rapidly lower core temperature

Core Temp. Cooling Rate (ºC/10mins)	IV Temp.(ºC)	IV Volume(L)	IV Infusion (mL/min)	Pre IV Core Temp (ºC)	Reference
0.39 ± 0.05	2	0.84	28	38.8	McDermott and Atkins, 2023
0.63  ± 0.05	22	2.00	66	39.4	Morrison et al., 2018
0.72 ± 0.06	4	2.00	66	39.3	Morrison et al., 2018
0.80 ± 0.11	20	2.00	84	39.9	Sinclair et al., 2009

This conclusion is further supported by the Wilderness Medical Society Clinical Practice Guidelines (2024 update), which state:

"Cold intravenous fluids may supplement cooling but have not been shown to adequately serve as a primary treatment for heat stroke. We recommend not using cold intravenous fluids as a primary cooling modality for the treatment of heat stroke" (Eifling et al., 2024).

Moreover, the November 2024 Consensus Statement on the Pre-Hospital Management of Exertional Heat Illness from the Royal College of Surgeons of Edinburgh emphasises that:

"Current evidence does not support the routine use of IV fluids, cold or otherwise, to reduce core temperature in exertional heat illness patients in a pre-hospital setting" (Hemingway et al, 2025).

The evidence strongly supports alternate cooling methods such as cold water immersion, whole body application of ice sheets or ice towels over IV infusion as the primary treatment for EHS. Regardless, administering IV fluids is utilised in some field settings as part of the prevention or treatment of EHS. For example, whole body ice-sheet treatment of military heat casualties (including some EHS cases) was complemented by either ambient temperature or 4ºC IV (Mok et al., 2017). That the cold IV cohort had a reduced duration of hospitalisation indirectly supports cold IV as a supplementary measure to more powerful cooling options. Another example from Phoenix Fire Department is profiled in the video below.

Figure 1. Phoenix fire crews carry IV bags on ice (Credit -Arizona’s Family (3TV / CBS 5).

In conclusion, while IV administration of cold fluids have a role in managing heat stress, they should not be relied upon as the primary treatment for EHS. Instead, IV infusion (cold or otherwise) may complement modalities that have demonstrated effective core temperature cooling rates.

Originally posted 10 December, 2025

References

Brearley M, Berry R, Hunt AP, Pope R. A Systematic Review of Post-Work Core Temperature Cooling Rates Conferred by Passive Rest. Biology. 2023;12(5):695.

Eifling KP, Gaudio FG, Dumke C, Lipman GS, Otten EM, Martin AD, Grissom CK. Wilderness Medical Society Clinical Practice Guidelines for the Prevention and Treatment of Heat Illness: 2024 Update. Wilderness Environ Med. 2024;35(1_suppl):112S-127S.

Hemingway R, Stourton F, Leckie T, Fitzpatrick D, Jones G, Wood F, Boalch A, McNulty-Ackroyd J, Thurgood A, Boulter M, Hartle A, Walter E, Pynn HJ, Kipps C, Stacey MJ. Faculty of Pre-Hospital Care: consensus statement on the prehospital management of exertional heat illness. Emerg Med J. 2025;42(6):390-395.

McDermott BP, Atkins WC. Whole-body cooling effectiveness of cold intravenous saline following exercise hyperthermia: A randomized trial. Am J Emerg Med. 2023;72:188-92.

McDermott BP, Casa DJ, Ganio MS, Lopez RM, Yeargin SW, Armstrong LE, Maresh CM. Acute whole-body cooling for exercise-induced hyperthermia: a systematic review. J Athl Train. 2009 Jan-Feb;44(1):84-93.

Mok G, DeGroot D, Hathaway NE, Bigley DP, McGuire CS. Exertional Heat Injury: Effects of Adding Cold (4°C) Intravenous Saline to Prehospital Protocol. Curr Sports Med Rep. 2017;16(2):103-108.

Morrison KE, Desai N, McGuigan C, Lennon M, Godek SF. Effects of intravenous cold saline on hyperthermic athletes representative of large football players and small endurance runners. Clin J Sport Med. 2018;28(6):493-499.

Sinclair WH, Rudzki SJ, Leicht AS, Fogarty AL, Winter SK, Patterson MJ. Efficacy of field treatments to reduce body core temperature in hyperthermic subjects. Med Sci Sports Exerc. 2009;41(11):1984-90.