My reactions now to nightshades, are either GI upset, and or burning at night in the feet and lower legs.

Potatoes do it within several hours or the next day.
Tomatoes do it faster, if concentrated. A little fresh tomato doesn't bother me, but concentrated sauces, or large amounts of tomato do get faster.

The longer you are off a suspect food, and then reintroduce it, the results typically are faster, than if you only stopped a few days.

Tomatoes have that histamine factor in addition to the nightshade factor so some of their reactions may be histamine in type added to the solanine. From what I have read lately solanine is additive and builds up in the body...that makes it more nasty than histamine which is eventually metabolized away when in excess.

I am very sensitive to paprika too. Paprika inflames my GI tract and I get burning there from it. And green chilies. But I can tolerate a bit of pizza once a week without difficulty.

I think people vary. I find the H2 antagonists (Zantac, Tagamet or Pepcid) helpful for the food reactions.