Invertebrates

Etiology: Injuries from cnidocysts (stinging cells) of hydroids, fire coral, jellyfish, Portuguese man-of-wars, and sea anemones cause similar clinical symptoms that differ in severity. Other invertebrates (e.g., sea sponges, annelid worms, sea urchins) have spines that can inflict painful stings.
Clinical features: Pain (prickling, burning, and throbbing), pruritus, and paresthesia develop immediately at the site of the bite. Neurologic, GI, renal, cardiovascular, respiratory, rheumatologic, and ocular symptoms have been described.

Treatment: Marine Invertebrate Envenomations

Decontaminate the skin immediately with lidocaine (up to 4%). Vinegar (5% acetic acid), rubbing alcohol (40-70% isopropanol), baking soda, papain (unseasoned meat tenderizer), lemon or lime juice, household ammonia, olive oil, or sugar may be effective, depending on the species of the stinging creature.
Shaving the skin may help remove remaining nematocysts.
After decontamination, topical anesthetics, antihistamines, or steroid lotions may be helpful.
Narcotics may be necessary for persistent pain.
Muscle spasms may respond to diazepam (2-5 mg titrated upward as needed) or IV 10% calcium gluconate (5-10 mL).