Symptoms in mild cases are localized pain, swelling, and redness at the site of the sting. More severe cases show additional skin flushing, muscle fasciculations (twitchings), hyperirratibility, hypertension, and muscle weakness.

Although symptoms usually subside in 15 to 20 hours, severely poisoned people may develop generalized muscle weakness, paralysis, and respiratory distress. Fatalities also have been reported.