Q: What possible impact does soaking in a hot tub after diving have on off-gassing and DCS? I see a lot of people going straight from the dive to the hot tub. Is this safe?
A: More and more resorts and liveaboards are offering hot tubs for clients, but getting into a hot tub after diving does alter decompression stress. As with many factors, the net response can be positive or negative, depending on the magnitude of the inert gas load and the heat stress.
The short version is that using a hot tub immediately after diving can increase the risk of decompression sickness (DCS). Heat speeds circulation, which may aid off-gassing, but it also raises the chance of bubble formation. Waiting 15 to 30 minutes before entering a jacuzzi is the safest approach.
How Heat Affects Off-Gassing
The longer version is that the hot tub or hot shower will warm the extremities and enhance peripheral circulation, which might facilitate inert gas washout (or inert gas elimination).
Large inert gas loads, however, can be problematic. Since the solubility of gas is inversely related to temperature, tissues will hold less in solution as they warm.
Warming tissue with significant gas loads can promote bubble formation. Since the warming of the superficial tissues precedes the increase in blood flow, such bubbles can pose problems before the increased circulation can remove them.
There is no simple formula to compute what constitutes a minor, significant or substantial peripheral inert gas load. The actual conditions vary as a function of the individual, thermal protection, physical activity and dive profile.
My approach is to stack as many factors as possible in my favour to compensate for the Murphy effect we frequently see in decompression sickness. I encourage a simple rule of thumb: delayed gratification. Enjoy the thought of the hot tub or shower for a while instead of jumping in immediately.
Safe Waiting Time Before Jumping in a Hot Tub
An interval of 15 to 30 minutes should help you avoid some of the risk, as will keeping more conservative dive profiles. Another compromise would be to employ a lower temperature in the hot tub or shower.
Frequently Asked Questions
Can using a hot tub after diving cause decompression sickness (DCS)?
Yes, immediate immersion in hot water may increase bubble formation and raise DCS risk, especially with high inert gas loads.
How does heat affect off-gassing after diving?
Heat increases circulation, which can help inert gas elimination, but warming tissues too soon can trigger bubble formation.
How long should divers wait before using a hot tub or hot shower?
delay of 15–30 minutes is generally recommended to lower decompression stress and reduce DCS risk.
Does water temperature in the hot tub matter?
Yes, very hot water raises risk. Using a lower temperature setting is a safer compromise after diving.
Are there safer alternatives than using a hot tub after diving to relax?
Yes, hydrate, rest, and allow your body time to off-gas before using hot tubs or saunas. A lukewarm shower is safer than a very hot soak.
This article was originally published in Scuba Diver UK #81
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