Are worms painful to cats?

They can be. One or two worms may never cause an obvious issue, but as the worms reproduce and attach onto the intestinal lining, that can be painful. Worms can cause ulcerations, bleeding, bloating, and those sorts of things. It can, over time, cause a lot of discomfort.

They can definitely become uncomfortable. Some of them do have GI upset accompanied by nausea and diarrhea among other symptoms. Especially if they have a pretty heavy burden.

I wouldn't say causing sharp binding pain, but they can make them un-thrifty, so they can affect their overall health and wellbeing. I wouldn't call it pain, but it would definitely impact their overall health.

Worms can be painful for cats. If a cat has a lot of intestinal parasites, it can cause intestinal wall thickening, bloating, and inflammation that can be uncomfortable.