I think if anything, people don't react much to these at all sometimes. They may get parasites out which they may or may not see - but a lot of people don't feel too badly at all. On the other hand, some people get really bad headaches, but this is not the herbs, it's a result of the parasites dying and releasing toxins into your body to get rid of. So you may feel like crap for a couple of days, but this is a good sign usually. You can avoid this by drinking lots of water and if you exercise, don't stop.
The one thing I've noticed and read a lot of is that the protocols used for a lot of "Paragone" products just aren't strong enough. 10 drops here, 10 drops there and sometimes that's just not enough. I go with Hulda Clark 's method - take two entire teaspoons of Black-Walnut hull tincture at the very beginning on an empty stomach, then Wormwood at night time, increasing the dosage day by day, and then cloves three times a day, also increasing the dosage day by day, the Black-Walnut only needs to be done once a week for the two week period, thus making it three times.
Now THAT protocol will not hurt you, and if there are parasites there, THIS will get them moving.