Also, have you ever eaten ice cream and THEN shellfish?
Any reacion would begin within 30 minutes to one hour of finishing the SECOND item. The severity depends on how close in time they are consumed. If I eat them together, I can’t take anything to dampen the symptoms. Last night I waited about 7 hours before consuming the ice cream, and a single dose of Pepto took care of it.
I’ve never noticed the order of consumption making a difference, but it might. I’m not going to find out.