Dylan had Nexgard spectra tabs, and no adverse effects. Out vet has now switched to Simparica, again he seems OK on that. We used to use one that began with A, I forget the name, but it made him itchy, ditto on our last cocker Milo. I prefer the tabs to the spot treatment for that reason.
Ticks are the problem here, but a flea infestation must be awful, we only ever get an odd 🤞. I do not see the point of ticks and fleas in the evolutionary grand scheme of things.