couple of thoughts from an ER doc on marine skin surface stings
Although hot water immersion HWI (104-110f) mechanism of action is contraversial the efficacy for pain control is not and should be utilized in conjunction with decontamination for any marine surface stings. Decontamination with shaving cream or baking soda will stop further release of nematocysts. removal of cream / soda with razor or edge of blade will then complete process. This process can be repeated during initial first aid. Rubbing effected area with hand or towel is not recommended for it can facilitate further nematocysts release. Using salt water for HWI is preferred over fresh for same reason. water discharge from motor combined with ocean water works well and is easily adjusted for appropriate temp. If pain persists beyond a few hours likely a secondary inflammatory response is responsible and the use of NSAIDs, steroids, oral or topical will be helpful. Oral are much better but not over the counter so go with what you have. A secondary bacterial infection is not likely to show itself for a couple of days with surface stings and in general will not be considered a cause of pain during first 24-48hrs. But if pain and or rash escalates over 2-3 days you may have an infection as well.
1) decontaminate with HWI, shaving cream/soda
2) continue HWI for pain relief as needed
3) ibuprofen, and steroid cream, +- on benadryl go with oral if you are going to use it.
4) once back on land consider being seen by MD if pain not controlled , oral steroids and pain meds may help
5) pain escalating beyond 24-48 hours is a red flag
5) anaphylaxis although not common can happen, epipen on boat not a bad idea.
adding a few thing to first aid kit may help next time
Ken
fyi, urine not hot enough to work but always entertaining to watch crying friend pee on himself