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Is warm water immersion effective in aiding reduction in pain and recovery of function post- marine envenomation?

Three Part Question

In [patients presenting with marine envenomation] is [hot water immersion] an [effective therapy]?

Clinical Scenario

A young adult was paddling on a sandy shoreline during their summer holiday; they think they may have been stung by something in the water. They are showing local signs of envenomation including erythema and swelling. Ambulance crews have given no treatment as they were unclear as to what action to take. You wonder if warm water immersion will be an effective therapy for reducing the symptoms.

Search Strategy

Medline 1966-11/04 using the OVID interface.
[exp marine envenomation] AND [hot water] AND [exp immersion] OR exp warm water. LIMIT to human AND English language

Search Outcome

Only two papers were found specific for marine envenomation and treatment with hot water immersion (HWI).

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Atkinson et al,
Cambridge, UK
Swimmers with marine stings ranging from jelly fish, weaver fish and blue bottle jelly fish

Treatment with HWI of affected area

Total of 99 reports of its efficacy in 110 cases from several papers.
Retrospective - Level IVInitial to complete pain relief HWI for puncture type marine stings appears very effective in reducing pain and discomfort. Evidence very unclear for HWI in nematocyst stings

Potential mechanism of action for HWI is reviewed

No methodology

It is unclear as to what the best way to give HWI is either by bath or compress etc.
Lee et al,
8 patients mainly swimmers or beachcombers presenting with hand envenomation from stonefish species.

Varied local responses to venom all treated with HWI alongside prophylactic antibiotics (oral amoxicillin).
Case series Level III evidence Clinically significant reduction in pain and complete symptom resolution Limb immersion in 450C water in seven patients was used as first line.

7/8 patients received HWI and this was the most effective therapy overall. One patient required surgical debridement where HWI was not employed due to an unusually severe reaction
Systemic opioids were freely given, which is likely to impair patient’s pain responses to HWI alone.

Local 1% lignocaine was given to several patients alongside HWI

Stonefish toxin is more potent toxin compared to some other marine envenomations


There are currently no randomised control trials comparing various therapies against HWI. It is also unclear as to what the best way to give HWI is, for example by either bath or compress. The exact mechanism of HWI in relieving marine envenomation is unclear. It is likely to be a combination of both marine venom protein degradation and modulation of pain receptors in the surrounding area; which contributes to the therapeutic effect of HWI (Muirhead, Lalwani). Although these types of stings are more common in tropical environments, there is still a high incidence of marine envenomation in UK coastal areas. Subsequently it is important for the multi-disciplinary team in emergency departments to be aware of this treatment option.

Editor Comment

HWI – Hot water immersion

Clinical Bottom Line

There is reasonable evidence to support the use of HWI for those suffering from marine type stings in the first instance. It is a readily available therapy and for most patients proves effective.


  1. Atkinson PR, Boyle A, Hartin D, McAuley D. Is hot water immersion an effective treatment for marine envenomation? Emerg Med J. 2006 Jul;23(7):503-8.
  2. Lee JY, Teoh LC, Leo SP. Stonefish envenomations of the hand--a local marine hazard: a series of 8 cases and review of the literature. Ann Acad Med Singapore 2004 Jul;33(4):515-20.
  3. Muirhead D. Applying pain theory in fish spine envenomation. South Pacific Underwater Med Soc J 2002;32:150–3.
  4. Lalwani K. Animal toxins: Scorpaenidae and stingrays. Br J Anaesth 1995;75:247.