Hot and Unbothered: Why Does Heat Treat Stingray Strikes?

By Sol Vu 

Why is hot water the treatment for stingray strikes?

Imagine it’s a beautiful day on one of our countless Southern California beaches. The sun is shining and the cool shade of the umbrella protects you from burns. The cool ocean calls to you so you walk over there. Cautiously, you dip a toe in before jumping in and splash around. You feel something brush past your foot and flinch before a sharp pain shoots up from your toe. It hurts and you hobble over to the lifeguard who tells you that you’ve just been hit by a Round stingray. They hand you a bag filled with hot water and tell you to put your foot in which helps. But as soon as you take your foot out the pain spreads once more. 

Why and how does hot water help treat stingray strikes?

Stingray bag photographed by Sol Vu

What’s in a Strike?

After being struck by a Round stingray, one must first worry about the damage done by their barbs. These barbs are sharp and have serrated edges which tear into flesh as they enter and exit the wound. Depending on where the afflicted area is, one must be mindful about bleeding out such as if you were struck in an artery. In addition, care to avoid infection should be avoided.

The pain goes beyond the physical however, because stingrays have venom on their barbs. This venom causes pain described as excruciating that can last 2 weeks. Although the exact components of Round stingray (and indeed many stingray’s) venom is unknown, we do know that venoms as a whole are largely composed of proteins.

              3D Model of a Round stingray barb photographed by Sol Vu

Building it Up

To understand why heat is effective to treat stingray strikes, we must first learn about how proteins are structured.

There are four levels of protein structure, though we will mainly be concerned with the first three [1,6]. The primary level refers to the polypeptide backbone. This is encoded by DNA and is formed by amino acids. The secondary level refers to interactions between backbone amino acids which will influence the shape of a protein. Tertiary is the overall 3D shape of the protein formed by interactions between side groups of amino acids that are attached to the polypeptide backbone. The fourth level is the quaternary which talks about multiple protein chains combining into one big multi-protein.

Some of the interactions between amino acids that happen in proteins are: covalent, hydrogen, ionic, van der Waals, and the effects of polarity [1,6]. Some of the bonds and interactions mentioned are weaker than others which plays a role in treating stingray strikes.

Model of a protein showing various hydrogen bonds from [1].

Breaking it Down

Because of the different interactions at play in protein structures, proteins are sensitive to environmental changes; different pH levels, temperatures, and the presence of other chemicals can all affect proteins. Change in a protein’s native or normal structure due to any of these factors is referred to denaturing [1].

So back to hot water, one reason why treating stingray strikes with hot water is effective is because heat will denature proteins [1,3,6,8]. Proteins will begin to denature around 40°C (104°F). Coincidentally, the human body can withstand 40-45°C (104°F-113°F) before there is danger from burns [7].

But, heat won’t affect all bonds/interactions that make up proteins so the venom will not be completely neutralized. For instance, hydrogen bonds are weakened by heat but the bonds between amino acids in the polypeptide backbone will likely remain [8,9]. At 40-45°C, some smaller proteins will be left intact as they are very stable [8]. So higher temperatures are needed in order to break stingray venom down more.

Time is of the Essence!

Treating stingray strikes as soon as possible are important to minimize the effects of the injury. Stingray venom will begin to spread upon impact. Hitting that venom with hot water as fast as you can will ensure that more of the proteins are denatured (or partially denatured).

And, even if the water is 40-45°C the tissue/venom exposed to the hot water won’t be that temperature. 

It’s All in Your Head (Kind Of)

Human biology and physiology plays a big role in why we use heat to treat stingray strikes. If you’ve ever suffered from muscle aches, you might know that heat helps to relieve that pain. Heat is an effective treatment for pain because of how humans sense things [2,5]. 

We have different sensors for different things in our body. Thermoreceptors sense the temperature [5]. The nociceptors are pain receptors. When exposed to hot water, the thermoreceptors send signals to the brain telling it that something hot is touching us. This will block out the signals from the nociceptors telling our brain that something is hurting us.
Heat will also cause blood vessels to dilate (vasodilation) and increase blood flow which will diffuse the venom [2,5]. Smaller amounts of venom will do less harm than large amounts [4].

Acknowledgement

Thank you to Daniel Erdody for assisting with research on this topic!

1. Alberts B et al. “The Shape and Structure of Proteins” Molecular Biology of the Cell. Garland Science 2022
   

2. Cheng, Jem L & MacDonald, Maureen J. “Effect of heat stress on vascular outcomes in humans” Journal of Applied Physiology. vol 126,3: 771-781. doi:10.1152/japplphysiol.00682.2018

3. Dill, Ken A. & Shortle, David. “Denatured States of Proteins” Annual Review of Biochemistry. vol. 60, 795-825. 1991.

4. Doupnik, Craig et al. “Bioactive Properties of Venoms Isolated from Whiptail Stingrays and the Search for Molecular Mechanisms and Targets” Pharmaceuticals. vol 17 (4), 488. Apr 2024. DOI: 10.3390/ph17040488

5. Freiwald, Jürgen et al. “A Role for Superficial Heat Therapy in the Management of Non-Specific Mild-to-Moderate Low Back Pain in Current Clinical Practice: A Narrative Review” Life (Basel, Switzerland). vol. 11, 8: 780. Aug 2021. doi:10.3390/life11080780

6. LePelusa, Andrew & Kaushik, Ravi. “Physiology, Proteins” StatPearls. Jan 2022. https://www.ncbi.nlm.nih.gov/books/NBK555990/
   

7. Martin, N A, and S Falder. “A review of the evidence for threshold of burn injury.” Burns : Journal of the International Society for Burn Injuries. vol. 43,8 (2017): 1624-1639. doi:10.1016/j.burns.2017.04.003
   

8. Koshland, Daniel E et al. “Protein denaturation” Encyclopedia Britannica. Sep 2025. https://www.britannica.com/science/protein.
   

9. Tang, Xiaolin Charlie et al. “The effect of temperature on hydrogen bonding in crystalline and amorphous phases in dihydropyrine calcium channel blockers” Pharmaceutical Research. vol 19: 484-490. April 2002. DOI: 10.1023/a:1015199713635

This post was guest written by our friend Sol Vu, in collaboration with Dr. Ben Perlman and the STABB Lab